Jim, I'd have to dig back to before SW '13 happened to get confirmation of these prices, but they're close enough for now. Remember that this is for SpeedWeek -- shorter events might be charged differently.
Rental of the unit, including drop off at the salt and pickup after the event: $95.00
Per cleaning (pumping out the used blue stuff, washing out, restocking toilet paper and hand disinfectant): $15.00 each time. The renter gets to decide how many times he wants the unit cleaned (i.e. once a day, once every two or three or four days, once a week/ once an event - whatever). As you probably have read while in one of 'em, the units are designed to have capacity for a ten-person crew working a 40 hour week. Extrapolate your crew's use of the unit from that estimate to come up with your own.
I don't remember the cost of a sink (water, soap, paper towels, refilling/cleaning), but I think I heard they're $40/event. That one I'm very hazy on, but I could get you the exact number if you really want me to do so.
As for you not being near enough to any toilets to see 'em from your pit - go back two or three posts and note that I've promised to alert SCTA to the situation about the pits being so big that there are times when racers and their crews are not near enough to even see units from their pit. I assume you did see that -- I'm just restating it so the casual observer doesn't think I'm trying to get off without any work.
I see that Stan Back has posted a comment about the potties and the wind blowing the fragrance toward the racer's pit, but I'll say that that shouldn't be a problem these days, what with Honey Bucket's pretty good cleaning of 'em. We had one in our pit. It was used by us and neighboring crews, and never had much beside the aroma of fresh blue liquid. It didn't get heavy use -- but it also didn't stink. It was about 25 feet or maybe a bit less from our tarp/trailer.