i have done both. ive bought btc, and ive bought mining gear.  cointerra and hashfast are only vapourware til end of december at most and then they will be shipping.  thats pretty close.  But i do agree, if you want a miner, NOW, you can buy KnCMiner (or BitFury).  Actually, KnC has announced a small delay so even they arent shipping from stock this minute.  Buying a pre-order of cointerra or hashfast gets you more hashing power for your money, but with a delivery date a month or two further away.