Never heard about them but I have tried Nortec Locating Services (vending.nortecco.com)and am satisfied with their service they always are able to find locations in the time frame they promise.
There are many other vending locating services. Locating business can be difficult so some time companies can't gurantee the time frame but I have good experience with:
Many of the locating companies do location by telemarketing so their location is not important, just make sure you deal with someone whom is going to be in business for a while and provide service with reasonable rates.
Try the company first, with giving them one or two machines to locate, all locators have different policies so if you try them first then there are no unpleasent surprises.
I have dealt with Notec Vending Services, they are in Canada but serve US market also, try them on vending.nortecco.com
I would suggest buy a batch of 5 machines and when locate them buy more and if you have a option of buying the used one that is the best way to go, also product do not buy so much in bulk just buy enough to sustain for one month as you have to experiment to find out what product work better.