The reason the answers you find are varied and vague are because people are very diverse in their preferences. While one person might like a very formal ceremony with all the trappings, another person might prefer a simple but elegant ritual. Personally, I haven't read about one yet I like well enough to even use as a basis for my own ceremony. So, needless to say, I've never had one.

Where can you purchase a collar? Anywhere. Wal-Mart, Petsmart, or a variety of other places like that have leather (real leather) collars for cheap. If you're looking to spend a small fortune, though, then you can always check the various adult product suppliers online. Ebay is also good for collars, but you need a credit card to access their adult products section. Which begs the question: How 'adult' is a collar anyway?

Vows? I'd recommend writing your own. I would also recommend avoiding words like 'doth,' 'forthwith,' and the other wide variety of neat-sounding but pointless verbage and adjectiveage that most people like to associate so much with these kinds of things. Think back to your wedding. How involved were those vows? Use that as your template.

Contracts typically suck. Period. Sorry to rain on your parade, but they do. 99% of the ones I've seen make the submissive out to be the household whore, maid, cook, butler, dry cleaner, gardener, pool girl, and landscaper. The questions to ask when agreeing upon a contract are: What's important to you? What limits do you wish to set (They can always be changed)? Are there any extenuating circumstances that will prevent you from "being submissive" all the time? Also, are you entering intoa 24/7 TPE relationship or is this just an occasional thing that you each will role-play?

Sorry for sounding blunt, but I'm trying to type all this before I forget it all or lose my train of thought.

Links:

http://castlerealm.com/library/roseritual.shtml
http://castlerealm.com/library/collar.shtml
http://castlerealm.com/library/morecollars.shtml
http://castlerealm.com/library/contract101.shtml
http://castlerealm.com/library/signing.shtml
http://castlerealm.com/library/dsrituals.shtml