If he said it was easy it must be cheap, ask him to explain to you again what he is planning on using so you can hear him and have him level the tub.

The concrete slab under my hot tub has started to shift over the years, so it's not level anymore.

I was quoted $700 to pour a new concrete base, which included gravel and rebar. That's really the best option, but I was concerned that this price was going to be too LOW! I wanted to make sure they made it thick enough that it wouldn't shift again in 5 or 6 years.

I understand money being an issue, but that's really the best solution. Anything else, I think you'll regret in a few years and just end up spending more money to undo it.

Otherwise, the next cheapest option would be to build a wooden frame with deck boards (so it won't rot from touching the ground), get it perfectly level, then lay down thick plastic that overhangs the boards, then give it a layer of pea gravel, then fill it with leveling sand. Then cover it with more plastic.

My hot tub was going to require 10 cubic feet of leveling sand, which is twenty 50lb bags. But of course that will vary a lot, based on the thickness and everything.

I'm not 100% positive that the leveling sand wouldn't wash away, even with the plastic layers. I was TOLD that polymeric sand would be a better choice, but that's just hearsay. It's considerably more expensive, but it DOES say it's rain-safe in an hour and is designed for pool decks, so... maybe.

https://www.lowes.com/pd/CasaScapes-35-lb-Gray-Polymeric-Sand/1002635628

The hot tub needs a concrete base and of course it needs to be level and that is the first order of business . This is a simple job for anyone who has worked with concrete and honestly with no pictures I have no clue as to your actual situation . Is this the best spot for the hot tub ? I like them c\\lose to the house and also to the bedroom so maybe look at a possible different spot and please post some pictures. BTW yes the concrete needs to be thick enough to support the tub over time .IMO a prope base in concrete is a much better choice than the leveler but it will probably cost maybe even more.