Meh... with a 38 gallon, as long as you had enough live rock for biological filtration, and added partial water changes weekly, that should be all the filtration you needed.
However, if you do want to get a skimmer, i would look in to the CPR Bak-Paks and the HOB
Reef Octopus'. Those are amazing skimmers for the money. Only thing is.. i don't think you will find one for 70$. I got the lowest HOB
version of a reef octopus for my 55G, and it cost me 120$. The CPR's may be a bit cheaper, but im not sure because i haven't looked at them. It's going to be tough to find ANY type of skimmer out there for 70$.. Even the junky seaclones are 100$+. You may want to invest more money in a skimmer though..
But in the event, all you absolutley HAD was 70$ give or take a few dollars to spend on a skimmer, you could always check your local listings for used ones on craigslist. Or you can look on ebay for good prices on skimmers.