Pricing/Value Questiom

Long time lurker, first time buyer. QQ on pricing to be sure I’m not overlooking anything. Is pricing (take GeekTime for example) generally on a supply/demand (popularity) basis across different models, or are there differences in material (assuming all tier 1 quality) I need to be researching?

I’m looking specifically at a DayDate 40mm via GMF ($388) and a DateJust SS 41mm ($438) also via GMF. Both white dials. Logic would tell me the daydate movement/complexity would bring more cost, but the DJ looks to be stainless steel, so could see that being a kicker.

(Also - I recognize Clean may be the better option for DJ, geektime looked to only have GMF sourced on the site).

Last question - how often are TDs open to selling standalone bands? I see a Skydweller with an Oyster bracelet and the same watch with a rubber strap. Can I ask to purchase both bands with the watch?

I appreciate feedback here as I learn!