I wouldn't say to go for cheap
, but rather look for something solidly in the mid range that focus more on taste than aroma. If you like high mountain wulong, then look for Si Ji (Four Seasons). This is the best wulong I've had iced to date - the more expensive ones tasted better, but the cheaper ones were good as well (just not as rich). Si Ji in general is usually cheaper because it's harvested 4 times per year (each season, hence the name).
Many TGY's in the same range (lower mid quality) are also very good for this. Really anything with more taste and a simple aroma. Being more about taste than aroma means that there's less complexity. Complexity normally comes from the aroma, which would just get lost when iced leaving you with a mostly insipid drink. Simple but strong aromas, however, will still usually carry through after being iced. (Is it obvious that I spent a fair amount of time on this this last summer?)
Another good one to ice is Jasmine pearls
I got some locally that I like best, but then I really haven't tried any from the onliine shops. I also picked up an inexpensive jade Dong Ding ($30 for a half pound) for making iced tea.