So the Abrams is not too much more of a logistics problem than any tank is; the problem is that things meant to work with Soviet tanks are completely non-interchangeable with things meant to work with Western MBTs. It also runs on a gas turbine, which, being a jet engine, is pretty much able to be fueled with anything that will burn.
The logistics problems with the Abrams principally revolve around the fact that the thing is a 70-ton monster. Not a single ARV (Armored Recovery Vehicle), tank transporter, rail car, etc. in Ukraine is equipped to repair, get un-stuck, or move an Abrams. The Abrams is probably the best MBT in the world because the US needed it to do everything. It has to fight anywhere, in every environment on the planet, in any situation. And meeting that pushed the weight through the roof. In practical terms, much as I personally like the Abrams, it would be better for Ukraine to get some Leopard 2s. They're 10-15 tons lighter than the Abrams and will work pretty well.
As for cost, Wikipedia says of the Abrams that it is "Estimated in 2016 as US$8.92 million (with inflation adjustment)". Expensive but we're not talking jet fighters here. They could receive a lot of the things at the funding level they're getting, it'd just be an issue of also supplying them with ARVs and tank transporters and etc. etc. etc. the things that let a tank force keep going.
The Bradley is not a simple "uparmored motor vehicle"; it is every bit as complex as an Abrams. But what it isn't is 70 tons, so Ukraine's existing infrastructure can handle it. It's also not that vulnerable. Sure, we lost some to IEDs, but when five to ten 105mm artillery shells go up right underneath your vehicle there is nothing you can do about it no matter how much armor you're packing. Bradleys are at least resistant to the threats expected when they were designed, i.e. Soviet standard AT mines. RPGs will kill Bradleys because they're not composite-armored, but the only thing I know of that is is the Boxer AFV/PUMA (In German service). Baseline Bradleys were relatively vulnerable to a lot of threats, but that's because they're an IFV and not a tank. The general solution to things like RPGs is "your infantry will kill the RPG team first" and the solution to tanks is "dead center low, give 'em a TOW".
Basically, the Bradley isn't the be-all end-all of armored vehicle design but it is a solidly competent IFV, and more importantly it is a solidly competent IFV that packs a massive punch even relative to more modern vehicles of its class.