well, as far as i remember, the w0 comes in at least 4ohm and 8ohm, and apparently, also 12 ohm.
but since you have the 4ohm version (the sub should be called something line 10w0-4), then you are limited to three options.
1. either a two channel amp that can be bridged down to 2ohm mono (harder to find)
2. a mono sub amp that is optimized to run at 2ohm load.
3. a four channel amp so you can bridge to do a certain wattage at 4ohms per channel.
4. two separate two channel amps and brdige each on a sub. (kinda a waste of money and space)
there are other way to possible run the subs but these are the only ways you can do and still optimize the power output of your amp.
for you, I would look to either option 2 or 3, I would say you dont need anywhere near 300 dolalrs if you go with option 3, I can get you a decent amp, that does about 175-185 by 2 bridged at 4ohms mono, for around 200 bucks. email me if you are intereested...
also, I would save the money and not go with brands such as ppi, zapco, jl...etc etc, you dont need such a fancy name to power w0s, look to good brands that dont cost as much such as lanzar opti, usacoustics, autotek ss and sx line...etc etc...
okay, time for the impedance explanation, pl;ease note that i am not a electrical engineer and I may be mis using some tech terms, but the overall concept is what I am after.
basically, each speaker presents a resistance to the amp, the lower the impedance (ohm rating), the less the resistance the speaker presents to the amp and therefor, the amp puts out more power to it, however, this also means tha the amp generates more heat, and as a result, if you get an amp that is not rated to run at a certain impedance, it will not be able to disssipate the heat and burn up.
so, if a speakre is 4ohm, it will present a 4ohm load to the amp, if its 2ohm, its 2ohm, so on and so forth. now, when it comes to powering more than one speaker to a certain channel, you can hook up speakers two ways, in series, or in parallel.
in series means like a flahs light, the negative terminal of a sub is connected to the positive of the other, and then the remaiing positve and the negative wiring to the amp (just imagine hooking up a whole bunch of subs this way too, positive ot negative...negative to positve..etc etc), what this will do is add up the impedance presented to the amp, so if you hook two 4ohm subs in series, you present a 8ohm load for the amp(easier to drive, less heat , but less power).
in paralell is basically, you hook up all the positves of all the speakres you have, and all the negatives of all the speakres, twisted them in to one big positve and one big negative, and hook them up to the amp, what this will do to the impedance is is you add up the RECIPRICAL of each speakers and then flip the fraction.
so if you have two 8ohm speakers, you hook them in paralle, it becomes : 1/8+1/8= 2/8, you flip it and it becomes 8/2 and thus 4ohms is what you get.
you can also apply this with speakres of different impedance ( a 6ohm and a 4ohm for example) but you dont really want to power subs that way since the subs will get different watts sent to them.
anyhow, that was a long winded way, just remember, the final impedance of your speaker(s), be it one, or a 10000000 hooked up in series or paralell or a combination of both(two pairs of subs hooked up in series to get a 8ohm load can be then hooked up in paralell with each other and get a final 4ohm load), they have to match the rating on the amp, most modern day amps are rated to do at least 2ohm in stereol and 4ohms mono, with a few selected high current models able to go all the way down to .25 or .5 ohms in stereo and .5 or 1 ohm in mono.
phew, I type too much