Recession is eating all the available funds people are switching for less and less on whatever it is. Every sector is been hit by recession and slows down. Therefore, looking at the current economic situation it is not advisable in any case to invest more on anything.
Cost Effective Methods
My suggestion for the cost effective methods in affiliate marketing would be to market your affiliate program by means of search engine optimization. This is not so much investment as compared to PPC and other methods also this SEO gives results on a longer term as compared to PPC.
There are some simple things that could do in order to have some basic SEO on a starter level. Just search for keywords relating to your affiliate program and target those keywords in your SEO.
Stumbling your affiliate site could also prove beneficial and provide you with some targeted traffic.
You have to keep one thing mind when you opt for search engine optimization method that you bring only the targeted traffic to your affiliate site, as only targeted traffic could draw you some sales.