There is a whole section of the market for buying recipes and even crafted IOs. Though you can pop them or merit buy them as well....it'll just take longer if you have tons of inf already.
You can buy recipes at Wentworth's as well as salvage.
Other sources of recipes:
Common recipes can be bought for Inf at the invention table
Merits can be used to get recipes either through random rolls or direct buys (the latter are not really worth it for anything other than a few high value ones)
AE Tickets can be used to get random rolls as well
Alignment Merits (require Going Rogue) can also be used for random rolls or direct buys.
Defeated enemies drop recipes and you sometimes get one for completing a mission.
Finally, the wiki is your friend 
http://wiki.cohtitan.com/wiki/Recipes
http://wiki.cohtitan.com/wiki/IO_Sets
Note: you can sell recipes you receive as drops at a regular store. They're listed on the left side of the store's window, UNDER the inspirations which you can't sell.
Common/generic IO recipes sell for quite a lot at a regular store. Way more than you can get at the Market where other players are trying to pay the least to buy them. Their extra value was to offset the change to drops where you don't get a lot of junk TO and DOs that you used to sell.
Named Set IO recipes sell for quite a be less compared to Common IO recipes at a regular store. However, depending on popularity/demand, individual named Set IO recipes may be worth millions at the Market. Until you get a feel for which Sets are popular and which individual Set IO piece is extremely popular, you may want to check them out at the Market before deciding whether you want to sell it at a regular store.
Note: a crafted IO will usually sell for a magnitude or more than selling a recipe.
Note: often a Set IO recipe may sell for a chump change at the Market, but that may be due to it requiring an expensive rare Salvage piece (costing 1-2 million Inf). However, check the going rate for a crafted enhancement of this Set IO piece. The crafted IO enhancement may be selling for multi-millions Inf and thus may be worth your time. Note: take close look at the dates of its transaction history and those for a couple of levels up and down. Make sure the action is recent and quick. Don't get suckered by an anomaly.
Teams are the number one killer of soloists.
Warning: You will almost certainly experience sticker shock.
TONS OF INF, OLD SCHOOL: I have enough to get SO's for ten level 50's. That's over fifty million inf!
TONS OF INF, NEW SCHOOL: I have one and a half billion inf. I can buy any single IO in the game... except about three.
The good news is, you don't need a Ferrari, and you can get really good performance from a Honda. With a couple weeks of time for bids, you can "Frankenslot" for about fifteen million inf and get very good results.
The other good news is, you can also SELL at Ferrari prices.
I have market mini-guides [from a consumer point of view] in my sig. I don't think they're too obsolete.
Welcome back!
Mini-guides: Force Field Defenders, Blasters, Market Self-Defense, Frankenslotting.
So you think you're a hero, huh.
@Boltcutter in game.
Thanks for the "valuable" info, guys. 
I left when ED came out. I like some of the changes that have been made, but have a few questions for high level chars trying to catch up (40+). They have tons of Influence, but I'm not sure how to go about spending it. I think I understand how to use Wentworth's for salvage, but how do you go about buying recipes? Do I have to just do a ton of missions to get Merit and random drops?