Plumbing costs

My plumbing is coming to a close on a Oil/Solid fuel/ Solar Panel setup.
Can anybody please help me with the following queries:

How much does a Copper Industry 3 coiled Cylinder cost? My plumber was supposed to be putting in a tall 300L Stainless Steel Cylinder (costing c. 1800) but instead he has put in a 270 litre Copper Industry 3 coiled Cylinder (and its not the tall one either). He says it costs the same. I have checked on the net and rang a few places-prices are varying but it seems to be coming out at c. 800-900 for the cylinder. Should i be concerned that he hasnt used the tall cylinder from the point of view of efficiency from my cylinder.

He also now wants more money because i changed from wanting a full pressurised system to just pressurising the showers....surely this should mean it costs less. On this note he is charging €500 extra for a negative Head Pump...whats this used for?

Generally glass enamelled or stainless steel tanks are usesd on the continent. I would'nt use copper, as its not good with pressure. Call around for the best price a stainless or enamelled tank. I got a cheaper quote lately for stainless steel. You will need a single inmpeller pump to pressurize this system, and a break tank (cold water storage). You cannont connect this directly to the mains in Ireland, unlike the continent

The second system is unpressurized (vented). For this application copper will be fine, but you need a more expensive, less reliable, noisier, negative head twin impeller pump. Tis system is used almost uniquely in Ireland and the UK

Option 1 is competitive, but a far better solution.

Hope this helps