Did not buy off-steam allot because steam's rates are extremely high compared to even smaller merchant websites offering steam products Let alone forum merchants selling items at a small rate compared to theirs. I did buy few games though and the BTC payment option was good before. did not see it for a while so not sure if they did take it down or not.
I wouldn't call Steam's rates
extremely high, sure those websites that sell Steam codes usually sell them for less, but the difference isn't that big. Plus, by bying from Steam directly with Bitcoin, that's just another big company that has some incentive to keep offering Bitcoin payments.
And Steam also has a lot of sales which makes prices even better than on those other websites.