I think first before even thinking about buying a pair you might want to consider buying one animal and get some hands on experience with one.
You may decide that the species is not for you or get bored and one will be easier to rehire if that is the case.
If your intentions are breeding down the road then the further thing you want to do is do some research on genetics and possible outcomes.
Finally if you are looking for specifict mutations you will be much better off buying visuals or 100% hets, a pair of poss hets could be a long road to disappointment.