There are all types of the Marvel comics...
The original and regular release (1977) has a cover price of 30¢. The price is in the square in the bottom lefthand corner with the UPC code and it books in Overstreet for $45 in NM condition.
The rare is the same issue with a 35¢ price in the square with the UPC code. It had limited distribution and they estimate about 1500 made it out for public consumption. This puppy books at $700 in NM or more.
The cheap exist too. They reprinted them and they are the same and would be hard to tell from the original except for the 'reprint' text in the upper lefthand corner of the cover or on the inside where the information is listed at the bottom of page 1 or the price and issue # are inside a diamond without a date or UPC. Both 30¢ & 35¢ issues were reprinted, so be sure if you are going for the original and not the reprint you get pictures and can verify using this info.
Issues 2-4 had both 30¢ and 35¢ versions and the 35¢ is always the more rare. Because these were reprinted with both prices, again be careful. Issue 5 and up are all 35¢ cover prices. They reprinted issues 1-9 just so you know. Just look for that 'reprint' text or the diamond.
Darkhorse has also released several TPBs with collected issues that have been recolored and they are available at Barnes and Noble or Borders usually. Same stuff with brighter color. Not sure whether I like it or not. There is just no replacing the original.
There are also the 2 Treasury Editions and they were released in 1977 and I picked them both up for $10 recently...http://www.jedidefender.com/yabbse/index.php?topic=4670.0
Hope that helps and if you have any questions or need help with authentcity or identification, let me know.