@jackshebang The more you pay for a printer the cheaper the running cost. Compatible toner is much cheaper but I've always stuck to the genuine manufacturer's supplies.
@jackshebang Mono laser is the way to go. Do you need double-sided? Probably a good idea as running costs predominate. Brother HL-L2350DW (Β£94 Amazon) looks good. TN-2420 toner cartridge (Β£60 Cartridge People) does 3000pp i.e. 2.0p/page.