The prices for PV seems to be going down these days.
If you want to find out if 'kit' prices are good, you need to look at a bunch of web stores
and compare their prices..
Some 'kits' don't have some of the stuff you'll need and some are bare-bones.
I think that some places might be charging you extra, just to 'package' the kit.
I think some are using kits to sell off the low output panels they have left-over in stock.
One clue to look for is the age of the panels. If they were made a few years ago,
the vendor may have paid a lot of money for them back then..
And now, he's trying to recover his investment, by selling to you at those old high prices.
I've seen the same panel for sale at difference stores, at
very different prices.
In some cases the price is $500+ more at some stores..
I'm trying to use DM solar
Solar Panels as my reference point..
Just put some panels you like in the basket and see what your shipping is (per watt) and compare to what you find on Ebay etc..