Why are models of cars so pricey?

I have never found a '75 duster model anywhere even though I know there was one made...

if im not mistaking the most common 75 duster is the mislabeled dart sport ?

[ame]http://www.ebay.com/itm/AMT-ERTL-1975-Plymouth-Duster-Hard-Top-Kit-/400629511981?pt=Model_Kit_US&hash=item5d4761372d[/ame]

(at that price I might just bid on it myself)


there is this MPC kit (going for 31 as I post this, expect it to sell for about 70)

[ame="http://www.ebay.com/itm/Vintage-MPC-1975-Plymouth-Duster-Model-Kit-1-7526-In-original-Box-1-25-scale-/201002491414?pt=Model_Kit_US&hash=item2eccae9e16"]Vintage MPC 1975 Plymouth Duster Model Kit 1 7526 in Original Box 1 25 Scale | eBay[/ame]


and then there is the convoy chaser
not sure what it is, 73-75 dart sport ?
not a very accurate depiction with the tubbed rear end and 426 hemi

[ame="http://www.ebay.com/itm/WOW-FIRST-ISSUE-1976-MPC-SMOKEY-CONVOY-CHASER-KIT-MIB-amt-/191008831274?pt=Model_Kit_US&hash=item2c7903772a"]WOW First Issue 1976 MPC 034 Smokey 034 Convoy Chaser Kit AMT | eBay[/ame]