Questions on the GMT vs Submariner debate

[Garys]

I'm getting real close to buying another watch but after reading as much as I can in TRF I'm more confused than enlightened.

I've narrowed my search to three watches. I really like the polar Explorer II so I'll probably buy a cheap one for everyday wear, max $3k.

But this brings me to my problem. I really like the GMT(Black) and the Submariner style watch and am seriously considering buying one as well.

So my questions are...

I don't see much difference between the GMT & Sub except cosmetically. What am I missing? Don't the both have the same movement?

Why does the GMT typically sell for more? (I'm assuming similar watches, stainless vs stainless.)

I see references to changing the bezels of the GMT. Is this something that is easy to do or do I need to have a watchmaker do it?

I assume that the GMT will maintain it's value better than the Sub as it seems to be more popular?

My budget for the GMT/Sub purchase is about $5k max but I could spend a few bucks more if I had to but every time I look at eBay I get more and more confused about pricing. What the heck makes one GMT/Sub worth $5k and another $4k? There appear to be a large spread in pricing for what appears to be very similar watches.

Before everyone tells me to buy from a TRF seller I plan on contacting several TRF sellers before looking elsewhere.

Thanks in advance

Gary