slimline

Hello all just after a bit of advice I need to buy a slimline fan (12" puller) , been looking around and they really vary on price, was looking at the spal/kenlowe ones but theres some universal ones on ebay which are half the price, these must be as good right? or should i just play it safe...

Hey guys got slimline ballast hid's and dont have a clue where to fit them and also dont have a bracket and is just three screw holes, also cable isnt massively long and dont wana try even considering extending it. Have attached pics below and any info advice would be greatfully appreciated...