Couple of itaste ideas but both have built batteries with usb charging and even so - are my favorites: the vv v3 and the MVP 2. Low price great performers and both of mine have served me well for months.
The way I look at less expensive devices is that they are expendables. Hoping for two years but I'll take one year for one that can take heavy use and abuse and keeps on ticking.
I forgo the additional expense and carrying of batteries ( sometimes needing different sizes ) plus charger. Price of quality batteries ( nice to have four in rotation) + decent charger costs is more that another MVP 2.
I have two MVP 2s - first cost $40.50 and second $35 to my door.
Their are many things that can fail on an intelligent battery device: fire button, selection button, internal electronics, 510 connection, internal battery life, +? So, maybe having an internal non-replaceable battery for low price and ease of portability is not a bad thing.
Now, if I already had newish batteries and a charger for other devices - then my choices might be different.
Different strokes for different folks.
Hope you find a good performer at reasonable cost.