One suggestion: I know it's hard for an online store that's just starting out, but try not to look at it in terms of "the most economical" options. If you have quality products, and a decent website, then the make-or-break factor in your sale is going to be your SSL, and whether or not the consumer feels they can trust you. You don't need to go overboard with bells and whistles, of course, but there are a lot of options out there worth examining.
For example, one recent development is extended validation SSL, which is a little more costly but is universally regarded as more trustworthy (it's the one where the url bar turns green? maybe you've seen it on some sites). You'll have to go through a hearty review to get the cert, too, but it could wind up increasing your conversions quite a bit. So, try to look at it as an investment, the same way you look at graphic design or programming at this stage in development.