It really is up to you (as it's been said, you're going to be the one looking at them!). But I add my vote to getting three females, you're kinda male heavy.

Can't go wrong with Pastels, they brighten up anything and are within any budget.

One issue with spider or bumblebee pieds: they only have pattern on their heads. If you like pied patterns, that would be a no-no.

Personally, I'd get a Mojave and a Yellowbelly to pair with the Pied and one day make White Golds and Pumpkin Pieds, respectively. The mojave also lets you make the BEL with the lesser.

Again, though, it's all up to you, but Mojaves, Pastels, and Yellowbellies are all well within most budgets, and if you have money left over, you can invest it in another rack so you have room for more! (I'm totally an enabler.)