Your job doesn't require anything in particular, except that if you don't want to have to reload the paper tray you'd want a model with an addt'l tray add-on (option).
Almost all, even most of the lower-end laser printers support duty cycles of (1000 x 3 x 4.3 weeks/month) = 12,900 pages per month duty cycle.
In other words, you're looking for a laser printer assuming this need not be utmost photorealistic quality. Beyond that, total use vs initial cost vs operationg cost (cents per page), and other requirements may dominate, like whether it need have networking support.
My last larger color laser purchase was a Lexmark C770, which does a great job but has a very annoying tendency to take over 90 seconds to warm up and "calibrate" itself after sitting idle for long enough to go into power saving mode (which by default is either 10 or 20 minutes, IIRC), before outputting the first page, despite the fact that they advertised only (forget the exact number, something like...) 22 seconds to first page. Despite reasonable output I can't recommend Lexmark printers for this (what I consider misleading if not defective product) problem.
One other major player in the market is HP. Since you have to start somewhere, look over their offerings and see what fits your other criteria besides the fairly modest need to print 1000 color letters 3 times a week. Frankly at this volume level, I suggest getting a printer whose color cartridges hold a minimum of 6K pages worth of toner, as it's too much of a bother to keep dealing with a cartridge running out prematurely on larger jobs, having them interrupted partway through. The larger the cartridges the better in this case, especially when interrupting jobs costs money in a business environment so it will tend to cost significantly more for a printer large enough to accomdate larger (than 6K) capacity cartridges, and these printers get very large and heavy, so where you need to put it becomes another factor as it's not mobile without several people unless on a large, very sturdy wheeled cart.