The hose does not need to float as it is a water lift not an airlift. Even with airlifts a floating hose will not deliver material to it's destination as well as a progressive slope. Think reverse plumbing as you are moving material uphill instead of down. If you are moving material a long distance you have to be cautious not to "over feed" the hose.

If you wish to cut down on the overall cost you do not need a flexible hose the entire length. Just get some regular PVC pipe and connect into that. The flexible collapse proof hose just makes it so you can manipulate the "working end". All you need to accomplish once you have gotten the material to this point is keep it contained and heading the direction you want.

As both liquids (water being introduced and surrounding natural pond water)are the same density the one with the material in it is slightly heavier which is why you have to be careful not to over feed it. All that will do is result in clogs and sometimes you may have to back flush the system other times it requires a partial take down.

Finally you are correct in the cost of hoses it is what will get you financially they do cost more than the pump often. Perhaps if you can locate a company nearby that uses suction style hoses they may have some worn or old ones that you could take off their hands for a more reasonable price. Most of the 3" suction hoses appear to run from $80-$120 for 20' when shopping take into account if it comes with fittings or not as fittings also can get pricey.

Apologies Palmerdad for semi jacking your thread but it still seems to be on topic.