If you want to start a business this could be a great way to get it going quickly. I think you should put the cost of half the honey in perspective when evaluating the deal. I would ask around to other local beekeepers who are in it as a business what kind of total yields they get in a year. Calculate it out for 30 hives x 3 and then get a revenue value for half that (retail or bulk depending on how you want to sell it). Then you will have a good idea of what it will cost you in dollars.
In my first year my hives produced on average 60# per hive, and that was just starting out in early summer after missing citrus flow. I think around here local honey sells for $5-6/lb retail. That's $900 in 3 years or a total cost of $450 per hive, less 1/30th the value of the extractors and other equipment that's in the deal. That of course is to be calculated after you see it all. From where I sit, it sounds like pretty expensive hives.
On the other hand, you have ZERO cash out of pocket to get in the deal. That's a huge positive term in your favor. :-D
Here's an idea. Offer to take the hives off his hands and propose no honey split the first 2 years and then all honey the third year. The argument is that you need to build cash reserves to get the business rolling - for new equipment, supplies, jars/packaging materials, marketing, accounting, legal, office supplies, repairs and maintenance, all those expenses you will incur to get started as a real business. By year 3 you'll have expanded way beyond 30 hives, I would imagine, and will still be able to generate income from your newer hives while paying off the whole deal at that time.
If that doesn't work for him then I'd offer no honey the first year, half the second year, and then all the honey the third. Then it's the same amount of honey just distributed differently...whatever you can negotiate you know. It's just the idea of generating the largest amount of revenue up front for seeding. Cash now is always better than cash tomorrow.
My point is, depending on what equipment is included, he isn't just giving away his bees, and you want to hit the ground running without being strapped for cash. So whatever your ultimate goals are, whether it be just to keep doing it as a hobby (in a big way) or turning it into a real business, negotiate in a way that gets you more cash earlier. It doesn't sound like he needs the cash immediately if he is offering to receive future honey. Otherwise he's be on Craigslist trying to sell everything.