Bougainvillea

I was down in the valley earlier this summer and saw a bougainvillea plant on sale for five dollars.   I love bv, so I thought why not, I'll just plant it and call it an annual when it dies in the winter.  Since the first of our summer was kind of cool, it didn't do much.  Either that or I planted it in too shady of a spot.  But it's finally starting to bloom again, and now I'm considering doing the "prune and mulch" thing so that it will be back again next year.  But then I ask myself, "Is it really worth all that trouble for a five dollar plant?  Shouldn't I just buy a new one next year?"