Hi and Welcome Steve.
£2,000 is a good budget and you can pick up a very good example for that amount of money. Even a car with sub 70k miles as well.
Original black cars are very rare, but Mica Blue and white are very common. My first MK1 was red and it was a PITA to keep red all the time! You can get two different variants of white:
Superwhite 040 & Superwhite 043 - there is a distinct difference in colour so be wary if you get a 1989 MK1 as this way well be 043 - it's only a pain when you find you cannot get body panels (albeit second hand) that match you paintwork as most are 040.
http://www.toyotareference.com/mr2/1985-1989
Good luck in your search.