Im going to Las Vegas in April.

Im just wondering what the difference is as far as donations go
for agency providers vs independent providers ?

Its about the same.  

When I did research, the majority of independent providers varied between 200-600 an hour. The Agencies I viewed started at 300. There are a few ladies 1k to 2k. I'm sure some of the agencies that handle porn stars are about that as well.  
Very wide range in Vegas, as there is in much of the major cities in the country.
 

In a very general sense (I'm sure there are exceptions), independents charge more. You might think the agency would charge more, to compensate for the fact that the income from each girl's appt is shared...but, it's actually more advantageous for them to maximize the amount of clients each girl sees per day, by making the price a little cheaper.  

For a $400/1 hour appointment for an agency girl, say the split is 60/40 in favor of girl. She keeps 240, agency keeps 160. If the agency bumps the girl's rate up to $500...the girl makes $300, the agency makes $200. Not a whole lot more...and, note the girl will see fewer clients at the $500 rate. BUT, if they cut the girl's rate to $300, she might book more appointments. Say she books 2, where she would've booked 1 at 400 (or zero at 500). Now the girl makes 360, the agency makes 240.  

Just to give you an example...I worked for an agency at mid-price range...I saw up to 8 clients PER DAY (wasn't that often, but more times than I can count)...2-3 per day was average. When I worked as an independent, I almost doubled my rate...I saw one per day most days, none per day some days, and on very rare occasions, I'd see 2-3 per day. But I could afford to price myself higher and see fewer men, since I didn't share the fee.  

There are exceptions. Some independents are higher-volume and some agencies do not operate by the revolving door business model. But I worked for a few agencies, and I was always lower-priced and busier than I am as an independent

I think it is pretty equal.  Of course, we're only talking averages.

There is a wide range of donations for both agency gals and independent gals. I'm sure you can find both within your budget.

This is not strict rule.It really depends.