I finally got my Atari 800XL fixed and purchased the Atarimax Maxflash USB Cartridge Programmer w/ Maxflash Studio Software. The software is incredibly easy to use and I was able to program 23 Atari 8-bit arcade XEX files to an 8mb cart - it only took a minute and I still had a lot more room on the cart for other games.
https://www.atarimax.com/If you already have an Atari emulator and Atari ROMS you want to put on a cartridge, you're ready to go and the system is extremely easy to use.
I never messed around with emulators before (I didn't because I was using original carts & 30+ year old diskettes) so my situation was a little different. Once I downloaded the recommended emulator and set up all the folders I needed, I just downloaded the ROMS i wanted from this (recommended by Atarimax) site
http://a8.fandal.cz/games.phpUsing the Atarimax, it's extremely easy to just "drag and drop" the ROMS (XEX or ATR files) into a playlist and program a cart like you would a CD from iTunes.
The carts are re-programmable. You can erase a cart easily.
It comes withAtari Maxflash Studio Software Installation Disk
Atari Maxflash USB Programmer
3rd-Party USB Cable
It does not come with Blank 8mbit Flash Cartridges (but Atarimax does sell them, and 1mbit carts separately)
Atari Games or Atari ROMs (but Atarimax website suggests websites to obtain the ROMS from and even suggests Atari 800 emulators to test them on before you program the cart)
I bought the Atarimax Maxflash USB Cartridge Programmer w/ Maxflash Studio Software for $60 and spent another $100 on 5 blank 8mb carts. It's a pretty hefty price, but I was able to condense my entire collection of games onto 2 cartridges and eliminate the need for my disk drive (except to play the Ultimas and 7 Cities of Gold). Plus, I have access to literally thousands of games I've never played.