Yeah, GTROM == goat-ROM == Cheapocabra, different names for the same thing. The board itself says both Cheapocabra and GT-ROM on it.
The $35 would be for the cart+shell+USB adapter. Buying just the cart+shell for a game release (or if you wanted multiple devcarts) is quite a bit cheaper, if that's what you mean.
GTROM is basically:
32kB PRG page
8kB CHR pattern page (2 pages)
4kB CHR nametable page (2 pages)
Permanent 4-screen nametable mode, so no mirroring to deal with
2 LEDs
And all those bits are combined into one register, so if you use more than one feature at a time you pretty much have to OR the bits together. That thread I linked has a PDF file (I just attached it the first post) which is still sorta incomplete, but at least lists the features.
Of course, normal NROM doesn't have 4-screen nametable mode, so it is a little different. And also, when loading programs (including NROM) you always have to leave $FFF0-$FFF9 unused, this gets taken over by the bootloader/CHR-RAM pre-loader. For those 2 reasons, you typically can't just grab any commercial NROM game and run it. Though it does work for some games anyways, I like running the M82 demo on it, that one works.
It is CHR-RAM based, but when an NROM program is loaded onto it, the bootloader will automatically load the CHR data before running the game.
To upload a program, you would turn the NES on, then run a command-line program from the PC that will write and then run ROM on the cart. I'm using an external program for testing and production, but I'm moving forward on a cart-based bootloader like I mentioned, so in that case nothing besides the USB adapter will be needed. The bootloader will have a configuration menu, and I'll make it possible to have the NES either default to run the loaded game, or run the bootloader when it starts. To get into the configuration menu then you would press a button combination when turning the NES on. Ideally I'll see if I can get a timeout mode working too, where it will run the bootloader and wait for half a second or so, and if there's no upload pending then it will run the loaded game.
The improved USB adapter I'm working on will make it possible to reset the NES from your PC (with just a small modification to your game), the cheaper adapter can't really do it. That should make testing a little more convenient.