Has found three sites
http: // www.cabelas.com/cabelas/en/templates/ho me/home.jhtml
http: // www.sinclairintl.com/index.html
http: // www.midwayusa.com/
What from them good?
The bullet is necessary for distant exact shooting on a marmot.
What will advise?
Berger Bullets CAL.243 105 Gr.MATCH VLD
Berger Bullets CAL.243 95 Gr. Match VLD
Berger Bullets CAL.243 90 Gr. Match BT
Swift 6mm, .243" 90 Gr. Scirocco
Nosler Ballistic Tip BT CAL.243 95 Gr
Hornady 6mm .243 105 Gr. A-MAX
Hornady 6mm .243 95 Gr. SST
Sierra 6mm.243 107 Gr. HPBT MatchKing
Sierra 6mm.243 100 Gr. SBT GameKing

For the .243 and distant marmot shooting I'd be tempted to start with the Hornady SST.....
Bear in mind that many bullets may have to be tested to find the accuracy you want.

For the last 25 years, I mainly shoot Sierra 85 gr HPBT Gameking. GREAT bullets!

I would ,think that the Nosler BT or the Hornady would be fine.

I know the Sierras are known for their accuracy. I would start with them and the hornady sst. I think Sierra makes a varminter bullet, like the blitz king. www.sierrabullets.com

The Speer 80gr spitzer is a very good varmint bullet and is much less expensive than most of the bullets you have listed.
I have not used it at long ranges, but get 1/4" [ 7mm] groups at 50 m.
Don

Sasha,
The Sierra 6mm 100gr Sbt gameking > S.D..242 B.C..430 @ 2800fps & above

I've dealt with Midway quite a bit over the years and find them to be efficent and easy to deal with...

My favorite bullet for the .243 for deer and varmints also...

You might look at the Hornady 105 grain A-Max. This bullet requires a 1:9 twist, like the other bullets listed that are above 100 grains in weight. I have a 6MM-284 with a Jeff Lawrence barrel that will shoot this bullet into 1/4" at 100 yards. Expansion is pretty violent as well - something you may or may not get out of the other VLD bullets. Roscoe