Need to set my seat back a couple inches. Where can I get a stem with a cantilever to position the seat further back? Not carbon, not gold plated price. No, I'm not gonna get another frame right now.

Thanks.

https://www.rivbike.com/product-p/sp3.htm

I s'pose that's practically gold-plated, but it's a start anyway!

Kalloy,Plain type seat Post,
Brompton Saddle Adapter Pin.. Adds a horizontal 7/8" tube,
clamping onto the top, of the other seat-post tube,
[which is also 7/8, 22.2mm]
then you put the saddle clip on The SAP.
with the clip rotated to take the saddle above it.

This Brompton Dealer adds a QR normal delivery is a pinch bolt,
the piece is threaded into one ear, for that bolt.
https://www.foldabikes.com/CloseUp/bike/sapMain.html

but you may have a clue about its usability, from the picture.

I,too, needed a setback seat post for my Cruiser. In the end I had to have it made at a welding shop of stainless steel. Could be an answer for your needs.

Warning!! Be extra careful of any ready made set back post on the market. They may not ,as was the case for me, as strong as they look. Two of the post I tried bent a block from my home.

Pictures, ho much set back do you need> I had to get one with Zero offset when I changed bikes. I ended up with a Thompson. But most bike shops carry a standard offset seat post as does Nashbar and Proformance. https://www.nashbar.com/bikes/Product...72_-1___202452
https://www.performancebike.com/bikes..._400002_400216

Here's the Kalloy:
https://www.universalcycles.com/shopp...1&category=758

Kinda heavy, but not unattractive

Try some triatholon retailers or forums. I've got a post moderne tri post that offers 44mm of setback. They've been offered over the years by Nitto, Easton and FSA among probably others. Keep looking and you'll find one. Also look for saddles that have a longer rail.

If this is to fix the relation of your leg to the crank, then you need a set back seatpost. If its to increase the size of your cockpit, then you'd do better with a longer stem. If you need more than 1.5" anywhere, you need a bigger bike.

Given then extreme amount of setback you want ?wrong frame size?
and the lowprice requirement.
You will probably need this:

Black Ops Layback Seatpost
https://www.amazon.com/Black-Layback-.../dp/B000AO9P02

It's a bmx post, so you will also need a shim to make it fit your frame.

This is one of the two post that bent like a wet noodle on my first test ride. Save yer money!!!!

The design is sound but the tubing they are made from is way,way to thin walled....like chromed tissue paper!