Tractor supply or any type of farm equipment sales company carries them. Might check with a drink manufacturer or bottling company. Any used for any type food product are a one use item. Can be bought CHEAP or maybe even free.
Check the search function above.

Ill check out plumbing supply places, Tractor Supply is on the pricey end and looks like all there stuff has predrilled bulk heads.

I think i want to start with a 100-125 gal 40 would worry me about just being big enough and no room for error, however i went to that site a few times shipping is a killer!.

Thanks All

I started out with 35 gallon barrel works just fine for me but it was free I still use it when need to take off the trailer when can not get close to the work site.

I would go with a 100 or 125 gal. tank.  The 35 or 40 will work just fine, but eventually your going to be doing larger roofs or multiple roofs in a day, and you don't want to be constantly refilling your mix. Time is money.  

Tractor supply sells a variety of tanks, but they are predrilled with bulkheads.     
Here's a couple other places to check.
http://www.tank-depot.com/
http://www.tanksuperstore.com/

Try Tank-Depot.

i got 2 55gal drums from a local building supply for $12.50 each. I also have a 225gal plastic tote from a honey dist company for $65. You can also check craigslist....good luck

Im haven a tuff time finding used, and all the plumbing supply places only have ones with pre-drilled bulk heads.

Looks like im going to end up going with that tank-depot, shipping is just sucha killer.

I just found one today,actually by accident.The guy I work for part-time owns a motorcycle junkyard.People around here knows he'll pretty much buy anything with a motor.Anyway,we went out to the golfcourse to pick up some things he bought.I knew we were going after a huge golfcourse thingy and an ice machine.I asked him what else we had to get and said,that thang over there.It was a 125gallon sprayer,which would be nothing(I don't think) to convert into a cleaner.It was only used with water,so no problems with 'Love".Sorry such a long story,but maybe you could check with your local golf course and see if they have one to get rid of.I know I'm hitting all of these around me now.Good luck

Will the 75 gallon fit in the back of a Ford F-150, just bstarting out here so I am trying to set up my Pickup truck to start out then work up from there.
Gilly