Today only there is a one day sale on the first volume of Spider-Gwen which you can get all five issues for $0.99 each ($4.95 for all five). As of now each issue is still currently selling at $3.99 and the MSRP for the trade paperback is $16.99, so this by far the cheapest option available. The five issues of Edge of Spider-verse are on sale as well, also for $0.99 each. Not only that but the first seven issues of Silk are on sale for $0.99 each. This sale is only valid for today so act fast.
If Spider-Gwen is not your thing there are some more sales going on this weekend as well. There is a across the board sale on Sandman Comics. Each of the 10 volumes is on sale for $5.99 each. This also includes other Neil Gaiman series such as Death, The Dream Hunters, and Dead Boy Detectives. All single issues of Sandman are also on sale for $0.99 each. This sale will go on until 11/16/15.
The Sandman issues are also on sale on Kindle, Google Play, and iTunes if Comixology isn’t your jam.
There is also Dark Horse Sale with first volumes of Hellboy, BPRD, Conan and the Goon on sale. They also have single issues of Buffy, the Strain, Fight Club 2, and The Massive for $0.99 each. This sale goes on until 11/15.
Last thing, if you want to buy any of these issues and are new to Comixology you can use my referral code here and get a five dollar credit toward your first purchase.