The dominant factor in the weight of a steel frame of a given size is the type of tubing used and lighter = more expensive. This will be mated to components that also follow the lighter = more expensive rule. As a rule of thumb multiply the frame and fork weight by four to get a target total bike weight: you can obviously go lighter at greater cost or save money and end up heavier.

Your Coda uses Reynold's lowest tier steel, given the wall thickness profiles (available here in PDF) the frame weight would be around 2kg and the fork another 0.8 or so. The bike weight is more than four times this; they've cheaped out a bit to bring the price down but that's what you expect at $600.

A higher end steel frame would use a higher strength steel, say 853. If you look at the chart in the PDF you'll see that the 853 tubes are thinner walled but they are generally used in a larger diameter to maintain the right level of stiffness. It's not hard to get around 1.5 - 1.6 kg with these tubes, lower if you try. These days you'd match this to a carbon fork, call that 400g.

The "Quest" (631 tubing) and "Eclipse" (853) models in your link are pretty close to my rule of thumb: the "Quest" frame and fork would probably be a little over 2kg total and the bike comes in a little over 8 kg; the price is a bit south of $2k. The "Eclipse" frame and fork will be a little under 2kg, bike under 8 kg, price over $3k.

BTW if you can get a custom made 853 framed bike fully built for $1500 you are doing extraordinarily well and someone is losing a bucket load of money.