If you want to print in oversized, I can readily recommend the Epson ET 8550.
It's a 6 tank A3+ photo/poster printer for under β¬800. If you got the use case for these (say as a photographer or an artist or you just want to print your own posters) then it's a really good model.
Unlike it's closest rival in the semi-professional market from Canon, the tanks make ink very cheap to operate, the vast vast vast majority of the printing cost is going to be the paper. It has a damn good printing quality even on mostly dark prints, it's quite fast for documents spitting them out in 3-5 seconds each so for personal use it's not meaningfully behind a laser. Quite variable, too, you can take the back off and feed whatever material you want in there with a huge clearance for thick plates to print on.
Sure, it's not something the average user ever needs but if you are looking for something like this, I can recommend it.
It's difficult to say as a lot depends on your specific use case and what you print and on which paper.
For my main use case, I bought a 100-pack of relatively inexpensive satin a3+ poster paper (so only 280g, but eh, they get put on the wall with something like poster strips or tack, I hardly need them to be thicker) which comes down to ~78cents per sheet. Ink usage is difficult to measure because my prints differ wildly in how much color is on them but my average so far seems to be ~50 cents per max quality a3+ print. So ~β¬1,30 per full size print if I want to be slightly pessimistic about it. But some of them were probably more like 85 cents total. π
The ink bottles really last a long time. Check your local prices but over here they cost β¬22 a bottle to replace, the printer has two blacks (one is pigment based for documents and stationary and so on), CMY and a 60% Gray, they all cost the same here but might be different for you. And then of course depends on what you print.
What I sadly cannot say is what A3 would cost, but scaling down you should be looking at roughly 20% less ink costs per print for full-size graphics prints, and then of course the paper you're printing on. But that's just mathing it down from my A3+ prints.
Thanks for doing the math. I have a deal with a commercial printer for slightly less, so it appears I won't be changing. Rather not have the hassle either, in fairness.