It depends
I thought all the UPT Reserve Squadrons paid travel (mine did), but found out some don't. There is also a limit on how many paid travels you get a year......not sure what it currently stands at (I'm back on active-duty). I think it used to be one per month.
As far as how much you can make: from 2005-2008, I worked almost as much as a full-timer--I could get all that I asked for. Now? Guys are lucky to get 5-6 days a month. It depends on how many Man-Days the squadrons are allocated, and under the current fiscal constraints, it is almost zip.
My best estimate (and again, I'm not in the Reserves any more) is 6 days a month of UTA, TP, and some of your AT. You can look up the pay rates for your rank and figure the rest.
Bottom line: used to be one could trough and make a living off of it; now it is just a supplement (but gives great flexibility to airline living).