Help with modding U5 projector spot light

Hello,
recently the auxiliary spot lights i use on my motorcycle stopped working as i think water went inside. so instead of getting new ones i thought why not try and replace the led with genuine Cree XM-L2. but the problem is i don’t know how to make a reliable 3v3a driver for it. i don’t know if the ones available on Chinese websites are reliable enough and to be honest i couldn’t really find any which works with 12v input ( motorcycle battery). stock ones don’t work anymore.

i don’t have any good tools either, just a solder gun and a little basic experience on how to do it. can you guys suggest me good reliable 3v3a drivers ? or maybe help with making one. thanks.

these are the lights i want to mod. - Amazon.com

You can find a DC to DC Buck converter that can step down your 12 volt input to 3 volts at 3 amps continuous. I remember seeing this one on Amazon. My son needed it for some RC Plane thing him and his uncle were into.

https://www.amazon.com/eBoot-MP1584EN-Converter-Adjustable-Module/dp/B01MQGMOKI/ref=sr_1_6?ie=UTF8&qid=1527884639&sr=8-6&keywords=dc+step+down+converters

but that is not constant current, right ?

also. how much light output really depends on drivers ? i mean i see some big brands sell their aoutomotive lights for more than 200-300$ which consists 2-4 Cree XM-L2 according to them. so where does all that money go.

bump