My dry bench top came from a salvage yard. I built the frame and diagonal support legs and bolted the whole thing onto the wall. It is deep enough to take Beseler 45MXTs. My web bench is a commercial steel sink unit that also came from the salvage yard (Urban Ore in Berkeley for the SF Bay locals). If someone is remodeling a kitchen nearby you may be able to salvage the top. One of the work surfaces in my first house came from a refurbished 'granny flat' (that's an in-law space for the American audience 8-) ).
You can use some strong builder's polythene to protect tables or as a basic waterproof spill surface. For the wet bench you could use a trestle table, but something more solid would be better for the enlarger.