I spent over a grand for my first one, but that was because of tools mostly that I won't have to buy again. Also, I vac-formed my first case, so my polystyrene stock cost me a lot because of trial and error,also the materials to build the table and heat box was over $100 on its own.
But in components alone, you're looking between $200 to $250 for a done-right portable from scratch. (vac-forming included)
And yes, XCVG hit it, don't cheap out, it's more expensive and costs more time than anything fixing mistakes.