If Q is the quantity of items you can make without exceeding $2000, then the inequality is 2.5Q≤2000, Q≤2000/2.5, Q≤800.
So to stay within budget you can make no more than 800 items, but, of course, when you’ve eventually sold the items at $P each you will have made $800P.
(The profit on each item is P-2.5 dollars. If you sell q items, your sales would bring in qP dollars and it would cost you 2.5q dollars to make q items. Revenue-costs is qP-2.5q=q(P-2.5) dollars profit.)