Not sure how many people read The Family Handyman magazine, But anyways a couple of months ago they had an article about building a work bench. They used cabinets with a solid core door on top. Using casters to roll the bench around.

Using all new cabinets, castors, door etc. etc. Said they had $400.00 invested in it. Sounds like a lot and it really is. But a really nice strurdy workbench with covered cabinets on castors sounds like a great deal. Finding used cabinets and such would bring the price down considerably. I like this bench idea so much i will probably build one this winter.
Not sure if they have the article online, If you search for it you might find it. even if you don't build it you may be able to use some of their ideas to build your own.
Kind of funny as now it's the only magazine subsription i have, not including the AMA magazine.