Avon Searider 4.0m is pretty unique. Solid build, flooding hull, deep V, hypalon tubes. They also made a 4.7m, but very rare to find. Old boats on the whole, so be wary of cheap deals, as there are plenty threads on soggy transoms and tubes that are on their last legs.
Difficult to compare, but Ribcraft 4.8m and Ribquest 4.8m are both excellent boats, deep V hulls (not flooding) with hypalon tubes. If Ribcraft is rare to find, then Ribquest I can't remember seeing their 4.8 for sale in last 5 years, and not for budget that would get you a decent 4.0m Searider.
This is expensive, but nearly new engine and trailer reflects in price.
https://www.theyachtmarket.com/boats_for_sale/1728155/
Odd example, but shows that these can be overpowered.
https://www.rightboat.com/gb/boats-f...59aff/rb254132
About as cheap as you can get, no engine, tubes have been painted.
https://boats-from.co.uk/avon/avon-s...er-23436/23438