Newegg offers the Silicon Power S60 120GB Serial ATA 6Gb/s 2.5" Internal SSD, model no. SP120GBSS3S60S25, for $49.99 with free shipping. That's $10 under yesterday's mention and the lowest total price we could find by $16, although we saw it for $5 less last month. It features read speeds of up to 530MB/s and write speeds of up to 520MB/s.
If you haven't yet, pad your order to over $50, then use Newegg's Android app and pay using Google Wallet to cut it further to $34.99. That gives it the lowest total price we've seen, excluding padding. (This discount can only be used once per account.)