So I gave it a try, to buy elsewhere and get some Steems into work. It is not so easy. Not really.
Poloniex trades Steem but does not let you withdraw. Old story, reported many times. They have certainly problems and I pulled out all funds of that company after they announced their new, user unfriendly and insecure terms of service.
Changelly lets you trade Steem, but it is a bit shady. There are a number of reports of ridiculous exchange rates around. Nevertheless tried to purchase Steem with Ripples from them. Good or bad, it was not possible to withdraw XRP out of Bittrex into Changelly, operation failed.
Big fish, to pay with and transfer Bitcoins for smaller amounts is simply unfeasible, way too expensive and very slow. That is valid for all and everything you do with Crypto/Altoins.
The solution…
What worked in the end, I purchased 2 batches through the steemit.com built-in Blocktrades. The first using Litecoin, worked fantastic, cheap, fast, it just worked.
For the second batch I had to trade my XRP into ETH on Bittrex and then did the same operation on Blocktrades, just with ETH instead of LTC, directly into Steem Power.
Blocktrades currently seems to be the best option available, just stay away from Bitcoins for any transactions. Put them in a cold wallet and sink that into a deep hole with some concrete on top of it :D
Mission accomplished and Steem powered up :)