Hi ,sorry for intrude your question.
But i think you can buy SP with some other cryptos besides BTC,Steem and SBD.
You can use USDT which is 1 to 1 with USD,and popular cryptos like Ethereum,Llitecoin,Dash and Dogecoin.
Also,you dont need to buy a full coin to be able to trade for SP,buy the one with less tax and with it buy some SP :)
Or even use BlockTrades Labor for USD directly,dont know how it works exactly as never used,but its an option.
Hope it helps,have a nice day! :)
Actually thank you very much for your reply. It is very helpful for me since I am new to the crypto world.
I will have something to look into now and try to invest in myself and in steemit.Hi @gambit.coin, No intrusion at all.
Thanks again for reading my comment and for replying to it :D