Mojave female for around $300, and a phantom male for $600. Or you can buy the female mojave now, raise her up, then buy a male phantom/mystic later to raise up so they can both be ready to breed. Phantom and mystic males should come down in price by then.

Alternately, you can get an axanthic female this year for ~500 - 700. Raise them up. Then buy a male spider het ax for probably $500 - 700 next year . Or you can buy a het axanthic female. They should go for pretty cheap these days. Maybe $150 - $200 I imagine.