Bass traps - foam cushiony items from Amazon ok?

I see foam style bass traps for about $25 that seem workable.  Maybe buy two just to test experience.  Are these good to buy?

and maybe than i can buy more pricier panels.  
I think there is a minimum critical mass for room acoustic treatments. Maybe start with 6 to 8 2'x4' panels and start there. 
It is highly unlikely that any foam thing for $25 will be an effective bass trap. You might find this interesting, an impartial video by a professional:
Post removed 
Just walk around your room and clap your hands sharply. If you can hear the echo, you need a foam panel on ONE of the walls.
Yes, that's reasonable, but it's NOT bass trapping -- it's treatment for slap echo, which is much higher frequencies.
Foam is really not a good acoustic treatment.  Sure, it's cheap, but I have had weird results with foam.  The best acoustic panels are made from fiberglass strands or similar.  The cheapest of these are from GIK (or you can actually make them yourself from something like Owens 703 panels (just google for ATS Acoustics). 

For bass traps, you really need a very thick panel (like 12-14" or more).  Either that or tuned membrane bass traps such as the Scopus series from GIK Acoustics.  2-4" panels are not effective at bass frequencies.
Artnovion seems to have nice panels, a bit pricey. Much nicer looking than the lower priced items and hopefully much higher quality.

i just want to get a hint as to sound improvement by buying the cheap foam panels before spending big bucks.  I wasted alot by not going better in buying spkrs, upgrading speakers is a very costly path. 
Artnovion and Vicoustic have the most beautiful products to my eye. But they are not cheap. The best value often is provided by GIK, who will provide a treatment plan for a small fee, refundable on your first purchase. Like others, I recommend panels made of rockwool (and fabric covered), rather than foam. It is far more effective acoustically, and it does not oxidize and deteriorate over time, which some foam does.
@jumia you won't get a hint as to the sound improvement in your bass by purchasing cheap foam panels. You will gain zero information.

It would be analogous to attempting to find out what someone's voice sounds like from a speaker by using _only_ the tweeter—it would sound like that person was mute.

You must use the proper product to achieve your goal.
+1 give GIK a call.
But gik has a 3 month wait to produce your order. I asked.

they do seem to know alot about accoustics.  Tough job.
Three month wait? I understand, we all get impatient. But the payoff at the end will be far greater than slapping up a few foam panels.

These work very well..

Checking on a deal right now, I need 8, total of 4 boxes..

I'm thinking a little more Art Deco on the patina.. Touch of Queen Ann, in other words cock that crown to one side.. Just like the Yanks.. :-)
The vri-bass resonators are interesting, but expensive and they offer no measurements, or pictures to see what they look like in a room.
Compare to the GIK soffit traps, which are about $250 each and are also effective around 50 Hz.
@jumia if you want to put together some simple bass traps for cheap, call your local commercial/industrial insulation company and ask for some dense semi-rigid fiberglass panels. Leftovers from a job or whatever. Then cut/stack them together into tall thick cubes or triangular prisms, wrap them in some breathable cloth, and place them in your room corners or wherever you want to experiment.
Erik, they are adjustable. They look like 2001 A Space Odyssey. A buddy has 12 of them, pretty interesting.. 24" tall and about 15" across. He wouldn't let me take one apart.. LOL Look like modified SonoTubes, but all fixed up..

A 16" x 48" SonoTube is 15-20.00 USD at Lowes or Home Depot.  I'm thinkin.. :-)

One tube inside the other with a slot cut about 2" wide on the inside one.
Top to bottom.  Fix a top to it out of plywood 1/2". Stand 1"slats upright on the lids in a star pattern, on the underside. Drill your 5 holes between the slats drop that top in the Sonotube. Silicone it in place.  Then slide it up and down for the control you want. Mark it, remove the inner tube dampen it with heavy fiberglass insulation and slide it back in place. The bottom the same way, just no holes.

On its side and use the bottom too (have to drill), 2 6 footers aught to do it, on their side of a room, holes either end slot facing out at a 45 degree angle..

It might need something like black hole for the inside tube liner add another 10-20.00 usd for something like a peal and stick..

I can make better ones for 200.00 for 3 or 4. The problem is the "I can make part", has just about wore me out.. LOL 400.00 tops for 4 NICE ones

Less paint or fabric covers. I think covering the tubes with mylar first and then with a porous speaker grill fabric..  The plywood lid would be easy to finish with a nice veneer add 10-100.00 per veneer, just depends how fancy you want it, ay? Bottom set them on spring packs if they are upright..

I tried building a variable helmholtz resonator once.  It didn't work out too well and didn't really do anything.  I found that tuned membrane bass traps worked a lot better.
Did you have enough to make a difference? Did you measure what peaks you wanted to tame.

They have to be tuned and with enough volume to effect the mode in that room.. A single or even 4 if 8 are needed still leave you without "ENOUGH" to treat the tones correctly..

It's a volume thing not a placement thing as "much as". Diffusion or absorption are different..  This works on canceling a certain peak or peaks.. The formulas are way over my head.. But I can read a mic sweep and see its effects on a given room.. Large will work, just fine smaller will not for BASS anyway..  Adjust the slot to change the frequency, pretty simple.  Just how much ugly can one put up with.. Starts looking like a Roman or Greek Temple.. Ahh that's the reasons for the columns.. LOL

Tuned the Temple..
Post removed 
I use pink fluffy 2’x2’x8’ superchunks in 3 possible corners of my room and the decay time is great, 20ms i think.....

start with trihedral corners

foam go good :0)