I have seen more and more comic book stores and vendors at comic book shows and conventions selling comic book bundles. There are certain aspects you should keep in mind when purchasing comic book bundles.
The Number Run
Some vendors and comic book store owners will place the first numeric issue in their comic book bundles facing one way and the final numeric issue facing the other way to tell you what the spans are of the comic book bundles are that they have for sale. Unless otherwise noted, do not assume all of the issues between those two numbers are present.
An Example
I was at a convention recently and say a vendor with comic book bundles of Batman Adventures. Each bundle had #1 facing one direction and #36 was facing out the other direction in the sleeve. I asked if all of the issues were present in the bundle. He hemmed for a moment and said that most were present. Since the bundles were for sale for $25, I automatically knew #12, which is the first appearance of Harley Quinn in a comic book, must not have been inside. I noticed someone purchasing the package and being very disappointed that the one issue he wanted was not included.
Comic Book Bundles with Number Slips
Some vendors will place number slips on the front of the package. I have found these vendors usually stay true to having all of the issues in the span included. If you are purchasing a four issue series, you should be able to tell if all four are present by counting the spines. With the larger comic book bundles, there is nothing wrong with asking to make sure.
Quality vs. Quantity
If you are looking for reading copies of the comics in the bundles, comic book bundles might be the best way to go since you don’t have to spend hours, weeks, or years trying to find every issue in the run you want to read. Typically, you are not going to find gradable copies in comic book bundles. Placing multiple issues in a sleeve will usually compress at least some of the issues to where they would have spine damage or other types of pressure damage. If you are looking to complete a large run of comics (say all of The Avengers from #100-#300), a buyer might not mind that some of the issues are not up to par with the others.
I have purchased many comic book bundles over the years and have learned that they are a great way for expanding a collection fast and for creating a readable run without effort. As long as you make sure the issues you are going to want are present and remember that (in most cases) and quality of the issues will not be gradable, you should be safe purchasing comic book bundles too.