There is no "Top of the line" ticket that can be bought.. that will get you in any NASCAR Garage. Garage passes for the Craftsman Trucks Series, Nationwide Series, and Sprint Cup Series can only be obtained by sponsors, teams, and the respective series. Getting passes from teams can be difficult due to sponsorship obligations. Each team is allowed a certain amount of passes for each week.. the same with sponsors. It can range from just a few up to 20 or more.
The best way to get in the Garage is start networking and getting to know the right people. It took me several years to get my first Garage Pass. Once you get a Hot, Cold, Truck, or Nationwide Pass.. you will hate waiting in any type of autograph lines. It simply amazing to turn around and see Jeff Gordon standing five feet away talking to Carl Edwards about a upcoming practice... etc. The thing with getting any type of garage pass from a team or sponsor is they are responsible for your actions what time you are in there. Since you are there as a guest of theirs.
As far as getting Gordon, or Dale Jr to sign more than one item at a time good luck. Not only are you having to walk ahead of these guys and keep up with them, but your having to fight with other collectors and pr guys. Not really fight but it dont come easy! The PR people can be a pain at times and can have you kicked out of the garage. So you want to stay low key. You can get several of the big guys several times.. over the course of a weekend. I usually just focus on 2-3 drives in the garage. The three I usually focus on is Gordon, Johnson, and Martin.
Also do not be fooled by "Pit Passes" alot of tracks will sell you a pit pass for $99.00 and say you will be able to get close to the action! Well.. kinda sorta not really. You may see a couple of the lower end drivers.. but for the most part with a "Pit Pass" all your going to see is the pit crew setting up the pit cart, Goodyear employees mounting tires on wheels, etc. You will be ushered off "Pit Road" about a hour before the race which is about the time it goes "Hot." Thats when all the bigger named drivers will leave the haulers / motorhomes and go to the drivers meeting, and introductions.
You will be able to get a few autographs on race day from the haulers. Several drivers will sign at the haulers. There will not be any HUGE names... usually Kurt Busch, Logano, Michael Waltrip, Etc. However there is always signings going on around race week. I know Tony Stewart does 20 or so autograph signings a year through Office Depot and Bass Pro Shop. Another option is check the speedways website and see if they are offering a package with a autograph signing. I know last year Indy, Charlotte, and Martinsville had alot of the drivers do autographs signing. Dont be fooled by the high dollar package for a Q&A. Because its just that... a Q&A... no autographs or picture withs.
Wish ya the best of luck... its not something that will happen over night.. my only advice to you is educate yourself about the hobby the best you can.. and be patient.