The price is probably "lowest" (or "cheapest"), but it may not necessarily be the "best deal". DL media is a lot more picky about how well it burns and plays back, especially on the second layer.
In some drives, sometimes RITEK DVD+R DL media is okay, for the burn. And then some players are pretty good about playing most any disc.
In general, however, Ritek manufacturer DVD+R DL media is infamous for putting out bad burns. Even when a burn is "good", players can have issues on them. This is not uncommon, even Ritek single-layer media is known for its poorer reflectivity (inability to play well in DVD video players). The Internet (blogs and forums, especially) are full of user complaints.
At least Costco has a decent return policy, should it be needed.
By all means,
test the discs after burning. Don't just assume that the burn is "good" because the burn was successful (or so the DVD burning software may have claimed). Testing information is found here:
http://www.digitalfaq.com/guides/media/dvd-tests.htm
TDK has not manufactured media in a while now. It's single-layer discs are CMC manufactured, while it's double-layer discs are Ritek manufactured. It's sad, too, as TDK-manufactured media was really good, back in the day (2001-2004).
Maybe you'll be one of the lucky few that ends up with no bad discs off the entire spindle of 50? It can happen.
The media is not "bad" necessarily, just not the most reliable for burning, nor the best performing for reading/playing.