Save yourself the head aches and just get a mixing board. I've listed some below which are relatively cheap if you still have less than $100 to spend.
I have
the EURORACK MX602A myself and I find it to be a very reliable and handy piece of equipment for my small setup, but there are other mixer sold by behringer that are still cheaper.
Can find theses mixers for less than $100 on ebay or at some online store.
http://www.behringer.com/MX602A/index.cfm?lang=ENG
EURORACK MX602A
6-Channel 2-Bus Mixing Console
Our MX602A takes compact mixing a step further, offering audio quality and flexibility you’d never expect in such a miniscule package. With two mono mic/line and two stereo channels, all with great-sounding 3-band EQ’s, a 2-track input and output, phantom power, phones output, balanced inputs and true main mix and control room outputs, it’s equipped to handle the most demanding of situations where few inputs are required. And thanks to its ULN circuitry, INVISIBLE MIC PREAMPs and impeccable construction, it’ll deliver professional results every time.
EURORACK UB502
http://www.behringer.com/UB502/index.cfm?lang=ENG
It may be small, but
the UB502 features the same state-of-the-art Invisible Mic Preamp (IMP) and the same Ultra low-noise (ULN) design for highest possible headroom as its larger brethren. Its one mono channel plus 2 stereo channels with a 2-band EQ on the mono channel make it ideal for use with fixed audio installations as well as keyboards, samplers and computer application. Hobby musicians and video makers will also find use for this ultra-compact mixer.
MSRP = $54.99
http://www.behringer.com/MX400/index.cfm?lang=ENG
MICROMIX MX400
Ultra Low-Noise 4-Channel Line Mixer
MSRP = $34.99
Despite its ultra-compact size, this 4-channel line mixer is big on features! It yields the highest sonic quality at all output levels, boasting ultra low-noise 4580 operational amplifiers for outstanding audio performance—the same op amps found in its much bigger brethren. Expanding on the capabilities of standard-size mixers is where the MX400 does extremely well, for example as a sub-mixer. If you are running short on available channels on your “big” mixer and need to bring the output of three different keyboards into your mix, you can simply connect them to
the MX400, work out the keyboard mix, and connect
the MX400’s output to a single input on your main mixer.
It will catch your eye because it’s cute as a button, but you’ll want to own one because of what it can do for your performance.