Buy your comics in person and pay cash! You will avoid the possibility of the post office damaging things, get to pick out the comics you want not just get a random assortment plus you get to see the condition of the comics you buy before you pay for them and avoid the dangers of sending a cheque in the mail or even worse paypal.
How can you do this?
Come to a comic book convention. I am a convention dealer who brings a van load full of Comics to various conventions in the midwest. The comics are a mix of mainstream comics from the past 35 or so years (Mostly Marvel & DC). I bring very few of the Image, Valiant, Marvel UK, etc from the 1990s (that no one seems to want) and most comics are in VF or better condition although there will be a few comics from the 1970s and earlier in lesser grades. They are priced a lot less than new ones are and way less than comic price guides would have you believe they are worth.
Prices vary depending on how many comics you want to buy. Prices start at $1 each, you can pick out 10 for $5, 50 for $20 or a whole long box of comics your choice for $110 (300+ comics). You will not find any of the dozen or so comics from the past 30 years that are worth more than $20 and actually sell for that, but you will find lots of A titles. I am constantly picking up more comics (46 long boxes so far this monthpast month) so there is almost always something new. Best yet most of the cons I set up at are FREE to get into.
If you are looking for more expensive comics, there are other dealers who have those.
Schedule until the end of June is as follows:
30 May Quad Cities IA/IL
31 May Omaha, NE
13 Jun Madison, WI
14 Jun Twin Cities, MN
28 Jun Metro East (IL suburban St Louis)
You can find details of these events at: www.epguides.com/comics