Since I had to make my decision really quickly (quite unusual for me - I usually spend way to much time researching in such cases), I was limited to the SSDs available in local shops. After few hours of desperate googling, I was about to buy Crucial MX300 2,5" 275GB SATA III (http://eu.crucial.com/eur/en/ct275mx300ssd1), but the salesman suggested the Goodram Iridium Pro 240GB (http://www.goodram.com/product/ssd/goodram-ssd-iridium-pro-2/) because of reliability (MLC memory and 5-year warranty) and I finally ended up with it - it's also quite fast, but I'm not very thrilled with it, since I know I'm not going to use it fully with the current rig (BTW: "Goodram" may sound tacky, but it is actually the only European RAM producer (https://en.wikipedia.org/wiki/Wilk_Elektronik), quite valued in Poland - I'm actually curious, if it's known anywhere abroad). Both drives were roughly 100$.
I only hope that my mobo is going to recognize it tommorow :O! Thanks Mike for your help!