A buy box is the written list of conditions a property has to meet before you'll look at it. Nothing more technical than that. It exists so an agent can say yes or no to a property without calling you, which is the whole point of giving him one.
Yours is closer than you think. "Under 200k, near me, makes money" needs three things added to be usable. Say how far near me actually goes, so 30 minutes from your house rather than near. Say what makes money means as a number, and the simplest honest version is rent has to be at least 1% of purchase price, so a 150k house needs 1,500 a month. Then say what condition you'll accept, because "needs paint" and "needs a roof" are different businesses. That's a five-line buy box and it beats most of the twelve-row spreadsheets, because you'll actually apply it.
On the tools: his MLS access, comp software and deal calculators come out of his pocket, not yours. Investor-focused agents commonly pay somewhere around 100 a month for a data service like PropStream and 20 to 40 a month for an analysis tool, and that's part of the cost of running their practice. You pay him through the buyer agreement you sign, and since the commission rules changed that agreement has to state your side of the compensation in writing before he works for you. Read that number before you sign, and if he says "we'll figure it out at closing," that's your cue to slow down.
The part people skip: a buy box you never revise is just a wish. Expect to loosen or tighten one line after the first ten properties he sends.
