I made a lap blanket out of Sugar 'n' Cream cotton yarn--made 22 strips of lace, then seamed them together. That plus the border was over 100 yarn ends to weave in. But, relatively speaking, it wasn't too expensive for a wedding gift for my brother. And because I did it in strips, I carried it with me everywhere to work on it. I kind of became the joke around my friends for a few weeks.
Beyond that, I'd never do something that big again unless it was for an heirloom, and then I'd invest in good yarn. Afghans take up tons of yarn and I have more fun whipping up one-of-a-kind scarves and hats to give away.
That being said, I know some people who have much-beloved hand-crocheted cheapo-yarn afghans from the '80s they still use, so while I'd probably end up hating the stupid thing before I was finished with it, the recipient might love it for many years to come. They're just not my thing!