Let me start by saying: if you want a spa-like experience, DON'T come here!
That said, I think this nail salon has the best price to quality of mani/pedi ratio of anywhere I've experienced in the city. The mani/pedi only costs $40 and they are very thorough. I've always found the tools to be clean and there is a reasonable selection of polish available.
The tradeoff is that the space is small and can be very crowded on the weekend, where you'll often have to wait 15-20 minutes. The ambiance is not great, but for $40 who cares?