I would also like to know if they are trustworthy...
Otherwise I'll buy from Scoop Distributions for R240 (ZAR, ex 14% VAT), which is roughly $36 USD. The RB750 is quite a bargain, since you get a Level4 license, and it doesn't even cost much more than the license itself!
The license key and invoice arrived as expected in e-mail after the payment. No problems, really $30 for Level 4 (:
Oh, one more thing. The e-mail didn't arrive to the address I gave upon purchase, but after contacting support from another address, I received the key there. Probably something was wrong with the first address.