No matter what brand you choose, try to find a double reed call with no cuts or simple cuts in the reed if you can. A straight double reed would be the easiest call to run, a ghost cut is pretty easy as well and probably easier to find from multiple brands. The triple reed call with a lot of larger cuts or patterns in the reed will usually be a little harder to run initially.
Check Walmart or Amazon right now. Our Walmart still had some cheaper diaphragms on sale last week and I've picked up some calls off Amazon this time of year fairly cheap ($5 a piece or less). If you can find them cheap go ahead and get a couple different cut patterns so you can compare the differences. Examples would be w cut, bat wing, cutter, ghost cut, etc. I would practice with different cuts now on cheap calls to figure out what you like, then move on to custom calls in the same pattern come turkey season.