That poses a real problem. However, if you so desire, I will help you out here and ship whatever you need to you via USPS, which has very reasonable rates to PR since it's a US Territory and they offer/have full USPS service. Of course, I expect you think I'm a scammer by offering such a service. But I have helped people do this before, and you can refer to my 100 percent eBay feedback. PM me if interested. The way I see it, it's the only way you will get good gear for your dollar. You might be able to find some eBay sellers that will ship to PR via USPS also, allowing you to get fair deals on good gear, assuming that gear available on there.
Personally, I think buying the stuff you pose to buy at CompUSA is throwing your money away, and I hate to see that, and that's why I'm offering to give you an option.
BTW, as far as the probability of my ripping you off, consider that I have even given away gear on this site in contests that I personally paid for. I recently gave away a $200 Behringer A500 amp to hifihoney in a contest, and a $60 PS3 game in a similar contest. I hardly have any reason to rip you off.
-Chris