Need Inexpensive Crossover

I'm using Monitor Audio GR-10 bookselves and a Klipsch powered subwoofer. Right now I'm running them both full range - and using the low pass on the crossover to have it kick in at about 80hz.

What I want to do is to roll off the low end on the bookshelves - as the bass sounds a bit too muddy at higher volumes (and just send the higher frequencies to the bookshelves - say above 80hz)...... and then just send the low frequencies (that aren't being sent to the bookshelves) to the sub (and probably not use the subs lowpass filter at all).

I know that crossovers can get to be pretty pricey, as all high end audio can. However, right now I'm a bit tapped out on the high end audio budget... and need something that will do for the moment - maybe I can upgrade lower.

Do I need something that has both a lowpass (for the sub) filter and a highpass (for the bookshelves) filter. Can one crossover unit combine this, or do I need 2?

I'm looking at spending no more than $100.

Is this possible?

thanks for the help (in advance)
check . I believe they have an inexpensive high pass filter.
Go to Item # 266-272. This is a passive low level high pass filter, 12 dB/octive 70 Hz. Including shipping it will cost you about $60 for two.

A better solution would be to spend more than $100, and get a real crossover. I suggest Marchand Electronics. They make several models, and if you can build a kit they are inexpensive.
Get a used Paradigm X-30 Crossover. It'll do exactly what you want to do. I've had one before and speak from personal experience.
New is $175 and used runs $100-$125.
Good luck!
Consider the Behringer DCX2496 (XLR in/outs, but RCA/XLR adapters are easily had).

Active crossover and digital EQ functions.

Under $400 new.

I have found it transparent in a $15K system. It's EQ function has tamed a huge (+15dB w/Rat Shack analog sound meter) 50Hz room node at my listening position. Given that competing products cost 10x or so more, it's a steal.

In many cases allowing your monitors to roll off naturally at the low end when augmenting the bottom octave with sub(s) will give better results, particularly midbass imaging and especially at low/moderate volumes. The Rat Shack sound meter (admittedly imperfect)plus your ears will allow you to use the Behringer to blend your sub in a more controlled fashion, possibly allowing a sub low pass cutoff well below the 80Hz, where the sub will actually be handling things like the bass notes of male vocals (yech).
The Paradigm X-30 used for around $100 is about as cheap as it gets...I have one. Not the best but well worth the money and will do what you want. For a little more the Outlaw ICBM used is even better. NHT also makes a low priced X-over.

OK. Here is the deal. For $64.99 (after rebate).

Behringer CX2310 Item 248-664 at parts express. It won't do all the wonderful things that a DCX2496 will do, but it is what you need. It's analog. Classic 24 dB Linkwitz-Riley characteristic.

I am amazed they can sell it for such a price.
Nice find Eldartford! It's a wonder you had the time, what with all the extra work Karls has handed you to read.

Sogood51...I happen at the moment to be researching X/O for my own purposes, so it was no big deal. I downloaded the DCX2496 Owners Manual, all 35 pages. It is huge overkill for home audio, but is really amazing for $400.

Yep, I took a look myself a while back. Even a better rebate going on that one! Behringer looks like they are alone at their price points in the market...I agree with you, I don't know how they can offer so much for so little.

P.S. Was just pulling your leg above regarding all the extra reading.

The Behringer 2496 is indeed a lovely way of making x-over dabbling a bit less tedious... with its full array of filter slopes and q. I had considered getting it to use as a tool in designing xovers for my spkr projects (including line level filters and passives). But the price, while excellent, was/is prohibitive for me :(
There is also Outlaw Audio's ICBM. While primarily designed for bass management for multi-channel audio (SACD, DVD-A), it can also be used as a 2-channel crossover. It has continuously-variable crossovers from 40HZ-up, and either maintains stereo bass output or combines low-level signals into a mono LFE-out.

New it is only $249, and I think there are some used ones listed on A'gon for under $200.
Sogood51...I did study the material on 1st order series X/O which Karls provided. (If you are there Karls, thanks again). Once you wade through all the greek alphabet it really doesn't say anything profound (IMHO of course).

Next thing I predict is a parallel/series three way crossover. Be the first on your block to own one:-)
Sumo had an old crossover that meets all of your criteria... Delilah
The X30 is very good,  although the ICBM is much better even if you only use the front two channels......I had both and I regret selling the ICBM.   
Those paradigm x30 are handy and sound pretty good. At a point I had 2 of them. 

When they say mini they arent kidding. If you can find these used grab one, used in the neighborhood of $100 or less
Sub already get  built  in low pass crossover, for bookshelf you
need 2 or 3rd  order high pass crossover with cross point about 100 hz
 it can be custom made using big induction coil.  The price for one
can be 50-60 each