Howdy Gang!!  I am relatively new to this forum and must apologize (pre-emptive apology) if this has been covered elsewhere or is in the wrong spot.
I have a pre ban Colt Sporter Match HBAR.  Bone stock at this point but that will probably change after reading about the various widgets on this forum.

1. What are your opinions and recommendations for must have spare parts?  
2. Which vendors and manufacturers would you suggest for such parts?

There seem to be endless amounts of both parts, manufacturers and vendors out there and I sure would appreciate some input from folks more knowledgeable than I.
Thank you very much!!

why not just get a "spare gun"

Quoted: 1. What are your opinions and recommendations for must have spare parts?

In order of importance:
1) Spare Bolt (this covers alot of potenital failures)
2) Spare firing Pin retaining Pins (easy to lose)
3) Spare Cam Pin (important part that must be periodically inspected for cracking)
4) Spare Firing Pin (just because)
5) Spare Hammer/Trigger Pins (1 or 2)

Now you can also get parts to rebuild the bolt like a spare extractor/spring/insert/pin, spare set of gas rings, spare ejector and spring.

Those are the key parts.  Personally I also have a complete spare fire control group (disconnector, trigger, hammer, springs etc.), and a spare gas tube/pin, gas key/screws.

2. Which vendors and manufacturers would you suggest for such parts?

Colt
Bushmaster (who BTW makes a very nice Field Repair kit)
Fulton Armory

In my own experience, I would recommend that the following spare parts be on hand whenever you are at the range:

- firing pin
- firing pin retaining pin
- gas rings (set of 3)
- extractor, ejector, and related pins and springs

I'm sure someone will suggest some or most of the fire control and other lower receiver parts, pins and springs, but it just may be cheaper to buy one kit rather than only some of the individual items.

I have used the following online sources for ordering such parts. All have proven to be reliable suppliers (in no particular order):
- Georgia Precision
- Del-Ton
- Fulton Armory
- Brownells (carries Colt pre-ban parts, IIRC)
- DPMS
- Midway

Prices for parts, delivery methods and minimum shipping costs can vary between suppliers, so shop and compare.

I'm sure someone will recommend Bushmaster, RRA and others, but I am listing only those I have done business with myself.

Brownells also carries DPMS parts. DPMS began life as an M-16 parts broker and subcontractor coordinator, eventually deciding to assemble complete rifles, and they market several "packages" of related pins, springs, etc. which might be more economical to buy than individual items, so keep that option in mind if your eventual shopping list seems to include a lot of such items.

Welcome to the Forum, good luck and good shooting!

Leave the Match HBAR stock!  Build a spare AR, then you can have it any way you want!

Thanks gentlemen.  That is of great assistance.  
I do like the idea of a "spare" rifle.  Dang.  On a Banjo Art Boy Budget that may take a bit.  I would like to build one and am perusing the forum and articles to figure that one out.
Before my daughter heads off to college and I am poor as dirt I do hope to do the AR build, a FAL build and pick up a FAL from a reputable builder.  Figure I'd better get my act together and gather such fun things prior to the college assault.  Also, no telling what the suits in Washington are going to try to do to us in regard to firearm ownership in the days to come.  Better stash em while I can.  
Again, thanks to all.  

Good luck in your efforts.

I'm sure the guys in the BIY section can help with build-on-a-budget suggestions.

My son & I saved $150 from a $725 street price 2 yrs ago building an Olympic PCR-4
from an assembled-upper-and-all-parts kit and buying a stripped Oly lower locally.
Instructions here on AR-15 to assemble lower and 2 hours later, voila! AR-15.
And not a burp from it since.