Be aware that there are many right ways to do it. (and some wrong ones that seem OK maybe) The trick is to pick one that makes sense to you (not just to the guy selling you stuff to do the job) and if it also makes sense to any advisers that you think are up on the topic then that may increase your comfort factor.

The best way is not always the most expensive and the cheapest way is frequently not the best way. You need to pick a solution that is GOOD ENOUGH for your purposes in your circumstances.

Time and money are often a trade off. If yo need to watch the budget closely then look for methods that get the job done with lowered materials cost knowing it may take a little more DIY involvement. If you can weld or have a buddy to help with welding you can save $ on the attachments to connect poles to piers. IF yo want to put in more labor and less $ and reduce welding yo can make your attachments from stock steel shapes cut with a hacksaw if you have no better cutting tools.

Sonotube isn't all that expensive but they don't give it away either. Add up the cost of using sonotube to extend piers above ground level for all your piers and the cost may surprise you.

You can make your own sonotube out of free cardboard if you don't mind a little dumpster diving (or similar) to get cardboard. Cardboard water proofed with used motor oil or similar and secured with duct tape or similar will do nicely.

You can usually trade your time in place of $ if you think about it.

Pat