Erk. Well, don't quote me or anything...I shan't be held responsible.
In general, back during Florida Project and Trade City time, you could get just about anything from the RSP, including LE 50 sets. Mostly due to the huge prices.
Last year, though, a handful of things did sell out the first round, and some other stuff was gone by the 2nd and 3rd buying options. For those that don't know, each RSP is for a quantity of 1- so the 1st RSP would get you your first of that item, then we do a 2nd in case you want 2, and then a 3rd in case you want 3. A 4th is done at the event, in case they have left overs or returns. Things gradually sell down as we work through all the RSPs.
So anyway- a LE 100 and 250 are likely to be gone in the 1st RSP if the character/theme/design is popular. With the new interest in pins (we were a little decreased in 2008-2010), more things might sell out, or normally I'd say even the 250s might be left over...
But then again, considering the lack of variety and prices this year, maybe not.