As I understand it, the Monero developers are planning a "network upgrade" (hard fork) for April 6, for the specific purpose of blocking the Antminer X3, and other ASICs, so no, I would not recommend buying one. Keeping ASICs from ruining the currency by over-mining it has been part of the developer team's goal from the beginning. Bitmain don't care at all, apparently, that the D3 can't even pay its own power bill, now, so they are certainly not going to care if the X3 is immediately useless. You might note that orders can not be cancelled, even before the miner is shipped. It may be that other Cryptonight coins will be mineable, though. Still, it is a real gamble to buy something that will not be shipped until June. Good luck!