I've found the newer devices of those I've made notes about here (http://www.cpmspectrepi.webspace.virgin ... pters.html
) O.K. - they're all "just a few pounds". However, WiFi dongles can be "power hungry" when trying to connect, requiring upto 500mA briefly, hence you'll need a good quality PSU and, depending on other USB bits & bobs "in use", possibly a powered USB hub. The small bluetooth dongles, like their cousins for other wireless HID devices, are less demanding, but you will have to download additional bluetooth supporting packages (for Raspbian) IIRC they're not part of the "basic image".
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, 2xB2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B+, P3B, B+, and a A+) but Buster on the P4B's. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm