how much would you say a good set up cost

Well, I would imagine the term "very good sounding" is probably very subjective and am sure most everyone that is in this hobby will say their system fits that bill. And I am no exception.

I have less than $2000 in my mostly vintage system.

Pair of McIntosh MC40 amps ($600)
Altec 604-8G Model 17s ($150)
CJ PV-10A preamp ($500)
Technics SP25 TT with ATP-12T arm ($60)
Denon 103R ($150) lightly used on Agon
Cinemag SUT ($160)
Marantz CC-65SE CD changer ($20)

The Altecs are nearfield monitors and I haven't done any room treatments. All is hooked up with inexpensive cables and wire.

I am sure it would sound different than a $16K system. But I doubt the owner of the $16K system is any happier with his system than I am of mine.

PK Modified Quad 57 Speakers $3900.00
Quad Classic II Mono amps 2190.00 Demos from Underwood
Quad QC 24 P preamp 1000.00 Demo "

Source and cabling of your choice, how about a Shindo modified 301 System for a total investment of less than your total budget of $30,000.00

Or a Rega P5 MM setup for around $10,000.00...cool!

I'm sorry, but with All Due Respect, it is a sort of meaningless / nutty question.
Compared to 99% of the world, I am wealthy. Yet, I have what around this 'neighborhood' is quite a modest system.
My neighbors think I'm crazy....they all have HTIB!
Maggie 1.6's retail for about 1800$
PS Audio GCC250 retail for about 3500$
CA 840c retail for about 1500$
Cabling / mostly BlueJeans maybe 200$ w/mogami XLR
HSU sub retail for about 500$
PS Audio Soloist outlet for about 200$
Home electric upgrades nearly 600$
OPPO 981DV 250$ delivered! bargain
Panamax Power conditioner 1000$
Room treatments (DIY) 500$ planned budget

Ok, so I've spent FAR more than I thought I had. It's like giving blood....a drop at a time....it all adds up.

The point? Depends.
1. How deep are your pockets?
2. How do YOU perceive price / performance ratio?
3. How influenced are you by 'keep up w/joneses?'
4. What is your level of obsessive /compulsive behavior?
5. Do you swap / buy / sell major equipment more often than 2x a year? (my system was stable for close to 20 yrs)

Remember, it's not a compulsion, it's a hobby....or is it the other way around?

A lot depends on what is meant by "a real good system. not over kill, just good equipment, good sound stage." The word "good" is highly subjective. Any Yamaha, Denon, Sony, Bryston, Mcintosh, B&W, Paradigm, ATC, etc. equipment will be good equipment - this is particularly true for the first three companies as their resources so outstrip the specialty companies that it costs little extra to ensure good equipment and the risk to their reputation precludes manufacturing junk.

As to the sound at all but the highest listening levels, my listening experience is that there is very little difference between a $2000 system made up of a budget CD player, monitor speakers, and a receiver (yes a reciever) and a $50,000 system. The differences are almost entirely in soundstage and accuracy and those I have found to be 99 percent dependent on the speaker. So, a good digital system can be had for $2000 a slightly better system for around $20,000. After that the returns are extremely small. But, of course, the hobby aspect tends to drive the system up but that is a different type, although very legitimate, type of return. Finally, the status aspect is completely dependent on cost, but also is a different type of return.

System Price = ego