If you get your terms sheet in as an advanced state as possible, including by looking at a template agreement which seems suitable, and draft things as clearly and comprehensively as possible, then when you consult a lawyer you will save time (and money) in not having to answer tons of questions, and depending on how good a job you do, the end draft may be based on the terms sheet/template agreement which you submit to the lawyer, which means the lawyer does not have to go digging through a precedents database for a starting point, saving time and money. Also it is the kind of project which lends itself to fixed costs (giving greater surety of budget) especially if you submit an ok first draft, and as the agreement on the whole does not seem especially complicated going to a small or mid firm should be ok which would be a more cost effective approach as well