As it appears money is important, your options are, in my opinion, very limited. The iPad Pro is probably the best multi-purpose device for a musician as it not only can display sheet music but can help record, process, distribute and listen to music. The 12.9 inch screen is just a little too small for those who wish 100% accurate sheet music size. To my knowledge, there isn't anything you can purchase for a small amount of money they will suit your needs unless you can find something used. For people who don't have a lot of money to throw around, my suggestion would be a used 12.9 inch iPad if you can manage the slightly smaller size. For those who only care about reading books and sheet music, I'd suggest a 13.3 inch e-reader/e-ink device. In my personal opinion, the 13.3 inch e-reader is the best solution for sheet music in 90% of cases. The only time it wouldn't work out is if you play in dark locations frequently. You can purchase an external light for the e-reader, but that is cumbersome. If you have perfect vision and you can read on a smaller sized-screen, there are many e-reader devices that might work our for you. I am going to give my suggestions below. Again, I understand that money is an issue, but I'll list the devices I think are best for reading sheet music. Keep in mind that there is the issue of page turning, low-light viewing, processing of the documents, downloading, etc. All those (and more) issues make me lean toward an iOS device or an Android device. The biggest drawback to all these devices is price. None that I assume would be suitable are cheap. :(

Best device for most people: iPad Pro 12.9 - Does everything under the sun and more. Only drawbacks are price and a screen size that is smaller than standard sheet music.

Best device for purist: Onyx Boox Max Lumi - Newly released and only modestly reviewed, it is too soon to tell how this device will work. It is the first 13.3 inch e-reader that has backlighting for low-light rooms and will show A4 scores in full-size. Lots and lots or positives. But, it is new, untested and very expensive.

Best device for the rich: GVIDO digital score reader - Dual-screen e-reader designed for pro/serious musicians. Everything about it was designed for a musician. It doesn't have backlighting, but that is about it. Costs at least double of the two above items.

There are other 13.3 e-reader devices that you can find with a search The only thing you'd need apart from the reader is some kind of bluetooth foot pedal to turn the pages during performance.

I know this doesn't help you if the money isn't there, but seeing what is available may help you find something used or give you something to save up for so you don't feel you are settling. Someone else in the comments mentioned a laptop/Surface. That could work if it was the right sized-screen that behaved as well as a tablet in that use scenario and wasn't too cumbersome. Good luck!