Im looking to buy a 1993 honda accord but only gears 1,2,3 and reverse work. what...
 

...should i do?

If you want that particular accord and get a really good deal buy it. if you are only driving in the city run it until it breaks. Otherwise you will need to have the tranny rebuilt at a place like Aamco or have the tranny replaced. You can find good replacements on places like Craigslist as low as $150.

Don't buy it and look for one that works.

don't buy it !! unless your planning on putting a new transmission in it after you buy it. That car is almost 15 years old allready. If they're planning on selling it to you for under $300 it might be worth your while. That is if you know a good mechanic who can install a new tranni for you.