[NickPoker]

The hand ranges on this hand would include anything the MP or BB would limp with that hits the flop.
A10 spades, Ax of spades, J10, J8, AJ, KJ, QJ, 88, 99, 107s, J7s, KQ, 89s, or any 2 spades. Without really know the players I would guess the BB for a missed draw, and the MP for a made straight (at least a two pair).

Personally, there are not very many hands I fold from the BB here, I not going to let you steal my blind very often for that amount of a raise. I fold the complete trash hands, but I am playing most connecting or decent suited hands. From MP's perspective, if my hand is good enough to limp, it is good enough to call your 2.5 BB raise, so his range would be anything he would limp with.

I agree with you that it is not that big of mistake preflop, but post flop you need to treat the hand like you limped (almost more cautiously because they are re-raising and calling you after you raised p/f).