They were simply the king of online bookstores. 

You can read a book and multiple books, but unless you are out there doing it (I.e. getting bids and getting contractors to truly get you an exact estimate) you will be far off from the numbers you want and may even lose money on the flip/rehab.The best advice I would suggest in my experience is that you should get into the line of work by either partnering with someone or working with someone on some projects prior to going into a flip on your own.

Quote from @Scott MacComb: I have had contractors just do a small list on a paper napkin, and some do something on a word document.

Stop hanging out with your deadbeat buddies who spend all day drinking, talking sports, and otherwise wasting away.

Hey man, congrats on the first deal! 

I've bought a ton of homes pre-foreclosure and at auction, happy to be a resource on that stuff, plus we just launched Bid Pirate, which is the one place online for NH, where you can see all the upcoming foreclosure auctions in one spot - you can learn a lot from the regulars at the auctions........ get after it, sister!

Our actual carriers used to be Secura, but they seem to be getting out of a lot of insurance lines or pricing so high as to have customers drop off, and we just moved policies in Nov. to Hanover Insurance. 

Does anyone have any advice on the best way to find these lenders?

Then you can read a more in-depth book like The Book On Rental Property Investing by Brandon Turner or The Unofficial Guide to Real Estate Investing by Spencer Strauss.2.

Most are folks that have the emotional control of a 5 year old, controlling attitude, an omniscient narrative in every thread & topic, act like an online hall monitor, and constant attention seeking.