If money is very tight AND you're new to power training, I'd also look at powertap.

Used (ebay) built into a open pro rim or new. Cheap, especially when compared to SRM.

You can use same cranks etc.

Racing with power is "cool" but it hasnt changed the way I race. Great to have data, no doubt but you're a kick ass racer and I dont think power will make you any more kick ass at races.

Use it to train on and get a disc cover for TT's (where having power data will make you faster). The open pro rim should do well enough for TT's where weight isnt so important and the disc cover is very aero at low cost.

You could also go a bit blingier and get a powertap hub laced into a HED ardennes rim (which is super raceable and sturdy enough for training).

Powertap's software (poweragent) isnt as good as WKO, but it's free and a decent way to track workouts.

but if you can afford a SRM, that would be the "best" option.