It depends on what you want to build and choose to buy.

Yes, new kits are generally more expensive than new kits were when we were kids.  Though I'd be curious to see how much kits cost in terms of how many hours you have to work to earn the money to buy them.  I suspect that while prices are higher, the amount of you have to work to earn the money is less, and the price is less, as a percentage of your income.

I buy a lot of old kits, particularly for airplanes.  My preferred scale for airplanes is 1/48, so my stash has a lot of Monogram kits from the 70s, with a mix of Revell, Aurora, Hawk/Testors, Fujimi, and some Tamiya and Hasegawa.  I buy them when I can find them the cheapest, at shows or on eBay.

For new kits, I buy Wave's MaK kits as they come out.  I do have new airplane kits, like Tamiya's P-38 and Dora Wings' P-43.  Those were expensive, it's true.  Still, I looked for bargains.  I bought my Tamiya P-38 from HobbyLink Japan, because they offered a discount, and with combined shipping, it was less than if I bought it from a retailer here.  I made a similar deal with the P-43.  I got it from an eBay seller in they Ukraine, who offered free shipping.  So I got it for about $45, cheaper than the retailers here have offered (so far).