That said, let me give you a couple of ideas about how to get the most out of the sugar sites without ending up with an expensive "pretend" girlfriend.
First off, Lester is absolutely correct, by definition these are temporary relationships and I have had several SBs where "temporary" meant one and done. It happens all the time, but as CDL points out it can be a lot of work to find an SB just to fuck her once. Unless you have a LOT of time on your hands it's probably a better to stick with pros if you are the kind of guy who never wants to repeat, BUT
I have a feeling it's not the repeating that bothers you, it's the idea that you are going to have to "spoil" her even when you aren't seeing her regularly and that is simply not something that you have to do to keep a sugar baby, or even several of them on the hook. There are a lot of SB's who will agree to see you once a week or even once a month for a lot less than what a "Well reviewed TER provider" will charge you, and most of the time there is no demand that you even keep in contact with her in between visits. There are very few hard and fast rules in the sugar world, you are only limited by your ability to negotiate. I have seen several dozen SB's over the last couple of years and I can't remember taking any of them on expensive shopping sprees. Some of my SB relationships entail going out to dinner, drinks, movies etc, and at least as many of them are purely physical.
The sugar bowl is a numbers game, I would suggest contacting a LOT of POT SB's, tell them what you are looking for and pursue the ones who don't require a "relationship". One word of caution however, the sugar sites under tremendous pressure to not allow their sites to be used for prostitution, make sure you avoid any statements that could be construed as soliciting a prostitute via their private messaging systems, and that includes terms like "PPM" Try to go to email or text as soon as possible to reduce your risk of getting kicked off the site.
And yes, Imp was correct in recommending you check out the "The Erotic Highway" board, it is the defacto Sugar board here on TER and you will find some guys, myself included who will be more than happy to give you our best advice to help you get the hang of things in the sugar world.