So my reservoir is leaking pretty bad to the point I put a coolant inside, and it leaked out a hour later.

How much is it to repair, and suggestions on what product is the best to replace it. Thank guys.

 

is it just a crack or like an entire chunk missing? how big? where?

 

Just a crack. When I put antifreeze I went outside noticed a puddle. It didn't gush out, but I slowly dripped.

 

I'd take it off and go to a wrecking yard with it to see if I could find a close match, unless you want to keep it looking 100% stock. Or do as I did when mine failed and get an aftermarket aluminum from Summit or Jegs.
JB Weld will fix the crack, but if it shows it's dark gray, and needs to be painted over the JB Weld to hide the repair.

 

I would take a Big Slam Mt. Dew bottle and drill and tap the cap for 1/4" NPT. Then tread in a barb and hose clamp the whole thing to the rad support. I have had to do this a few times. I have even seen it on drag cars with beer cans.

 

I would spray it with a rubberized coating to seal the crack (like PlastiDip or the stuff they use to seal rain gutters)...

 

I agree with Thor's comment. There's the rubberized stuff you see on TV and others at just about every store out there. I even saw that stuff at a local dollar store near my house. $10-$15 and you'll have leftover for other things. Damon has a good point though with an easier fix but if you want to keep your existing tank and not go junkyard shopping the rubber spray stuff does work.