Despite the claims of manufacturers, hardware differences play a small roll in performance times.

However, since you want spend, consider aero profiles as more important than weight since you're basically time trialling on a fairly flat course. If these are going to be reserve strictly for competition, you can go with low spoke count wheels, since their lack of easy serviceability won't be an issue (unless you crash).

I don't get involved in brands so won't steer you, except to remind you that as you get into better wheels, the differences as you move up become very expensive quickly, for only marginal benefit. So don't feel compelled to go beyond what you have budgeted. The rest is a matter of getting the engine working at full power.