Well first off, he can value his time however much he wants. As a partner at a major law firm in SV, he's incredibly busy so his time is extremely valuable (any distraction like consulting only makes sense at a rate of ~700 per hour for him) and as a partner, he's probably making millions at the firm. If he spent 5 more hours at the firm and was able to generate a multiple of what you're paying him for 5 hours of work (3500), then he's probably not charging enough, right?

If you want general legal advice for startups, talk to startup-friendly law firms. Many have packages where you give up 1-2 thousand bucks only for X number of hours + turning your startup into an INC or LLC or whatever + a small equity stake. For other law firms, you'll just have to talk to them and figure out what their rates are. Most are more in the 50-100 dollar range. Don't skimp on legal expenses, if you get sued for a few million dollars, you'll regret skimping on paying a better lawyer a few thousand bucks more.