Definitely spend the money now..if you try to nig rig a bunch of stuff you will end up buying a can fan/filter in 6 months and spending way more money on the long run. A word about filters though, I was a an HTG store in denver and the guy talked me out of going cheap on the filter...he said the budget filters, like the cheap one on HTGsupply.com arent packed well and the quality shows through the price. He said that you shouldnt be able to hear the carbon shake around in the can. The air will not filter through the carbon if it is not packed into a firm solid form, if its loose in the can the air will just divert around the carbon and will not be scrubbed of the smell. Basically he said go cheap on the fan, I got the 6" HO fan from htg for like 80 or 90$ and spent money on the name brand can fan filter. They are the most expensive because they are the best. A good initial investment saves tons of money in the long run!
Cheers,
JP