SSD technology has been maturing rapidly over the past two years or so. There used to be the SLC vs MLC (the former better but much more expensive) difference but nowadays all consumer class SSDs are MLC.
To be very honest, unless you are an extreme user requiring the fastest and best hardware, the average consumer will hardly notice any difference when the SSD speed goes above 100 MBps. The reason people feel that SSDs make the whole system "much faster", particuarly when they migrate from platter drives, is the extremely short seek time (no moving "record player" needle as in the platter drive).
I think just about the only thing to watch out for is the controller / cache of the SSD - if you see a real "bargain" which is like $100 less than all other similar size drives, you need to see if they have an older controller which may give "stuttering" problem.
The first generation consumer grade SSDs have a cheap jmicron controller which severely throttle the performance of the drive in certain conditions, causing "stuttering" of the whole system. However, I think most of these earlier drives have since disappeared from the market. The latest SSD controllers such as those made by Indilinx and Sanforce are very good, at least to the average consumer, and there is nothing to worry about.
Therefore if you find a "bargain", do some research to see what year / generation it is, and see if you can find some review on the particular series of drive. You should also do some basic reading on the web (Wikipedia and Google are your friends) about SSD stuff such as SLC/ MLC, controllers etc.