Will a standard 9V alkaline battery (300mAh- 400mAH) be able to supply 2.5A for 5-10 second at a time?
You might want to use rechargeable NiMH batteries instead of alkaline cells.

This Energizer AA NiMH cell is specified for 4.6A continuous discharge current, for example - way more than typical alkaline cells can provide. It'll probably provide even more current for a few seconds. Plus, you can recharge it!

Five of those in series and off you go.