Check some of the asian stores for inexpensive sharpening stones. I just picked up a combo 120/280 grit stone and a 400 grit stone (both 2" x 6" x 3/4") for $ 1.50 each at a Japanese store called Daiso, they are like the dollar stores but most stuff is $1.50 and better quality. I had to get a couple more because I left mine at my brother in law's cabin so that I have some thing there to sharpen knives with.
Here's another idea, sweet talk your parents into getting you a stone and keep their kitchen knives sharp for them. That way, they get some benefits from it too. Help out in the kitchen, especially when it comes to cutting stuff up. My mom always liked it when I'd cut stuff up, plus I learned how to do stuff like cut up a whole chicken in about 3 minutes or less, got lost of practice "hacking" up assorted vegetables and fruit. Now one of my favorite things to do is to slice up red onions for sandwiches and see how thin I can get the slices.
Let us know what you end up getting.
Ric