Andy,
If your not comfortable with your climbing skills hire it out. A Honey Loucust is not a tree for a novice climber. The wood is tough and hard to spike. Ever climb a dead tree like an elm or ash, same thing. Your more or less just walking around on the points of your spikes. Your chances of a gaff out and slipping increase compared to other midwest trees. The main stem can be rough and gnarly. The main limbs slick and smooth.
They are not hard trees to climb per say and offer many good rigging points for a removal. They are just hard to handle as the wood is heavy, tons of crisscrossed dead limbs everywhere in the crown. The limbs themselves like to hang together and fight you till they come free, it is like they have fingers on the end them. Locusts are aggrivating trees to work on.
I thought 56 DBH was a little big for Kansas. Glad to hear it was circumference. They can get that big but a loucst that big would be a timber tree and more in the way of a common H. loucust with those nasty thorn thorns a foot long.
4k's is way out of line for that tree. Even some of the prices quoted seem a little steep, from what I have seen of the pics. 2K would be a darn good price for a yard locust for a complete removal. If you can get your equipment in close to it without a lot of dragging and wood carting.
I'd hire your climber buddy if he is good and you and another person keep the ground work moving with your equipment. You can recoop your climber cost back in the winter selling the wood. Locust wood is right up there with oak and hedge . Trouble is trying to sell it that way as people have never heard of loucust as being a good firewood. Don't keep the wood over a year it draws bugs that makes it unsightly to sell.
Go for the job, it isn't that bad. Sounds like a good deal for you. Just make sure your saws are good and sharp.
I don't know if this helps or not but just my 2 cents worth.