They often have clearance suits for relatively little $.
But for my money, I'd get a Speedo Endurance fabric suit - jammer or brief. Jammer would be best for modesty (that's what I wear). The fabric lasts much longer than typical suits.
It may feel odd at first, but the drag reduction could be dramatic compared to board shorts.
Also, I recommend using a product called Suit Solutions for a rinse. It neutalizes chlorine. Put about 3 cap fulls in a bucket of water to use for a week to rinse your suits. Change the water out once per week. Really prolongs the life of the suit.