If you are talking about "affordable" handguns, why eliminate used guns? They are the best source for bargains for a shooter on a budget who needs a good, reliable defensive pistol. There are ways to reduce the risks associated with buying a used gun and, heck, even buying new these days is no guarantee.
If you just want to get into a contest as to which manufacturers have the lowest MSRP, you are also missing the point. No one pays MSRP. Comparing "street prices," even on new guns, is more relevant since that tells you what the pistols are actually selling for and gives you a hint as to whose MSRP's are most inflated.
The most affordable, decent new hanguns I know of are:
1. Bersa .380 - They run about $225 to $250 NIB. I don't even know what the MSRP is supposed to be.
2. CZ-75 in 9mm - The local Gander Mountain has two or three NIB, recent production, 75BD's for $350 each. Once again, I don't even know what the MSRP is supposed to be, but that's what they are selling at.
3. Ruger centerfire autos, especially in 9mm - Once again, I don't know what the MSRP is supposed to be, but they sell NIB for around $325 to $375, depending on the specific model.
If you open it up to used guns, the best consistent values (excluding "lucky finds" that are underpriced) are:
1. S&W "K-Frame" .38 Special revolvers - The .38's sell for less than the .357's, both when sold by private parties and when sold by distributers. That's a reflection of the lower initial purchase price for the .38's and partially because the .38's are less "versatile" than the .357's.
J&G Sales is selling Model 10's for between $170 and $200. A little searching will often turn up private sale guns for around $200.
2. Makarov 0x18mm - Bulgarain Maks go for under $200.
3. Ruger centerfire autos - Ruger pistols don't seem to hold their value on resale as much as some other brands. Maybe it's because the initial price is so low that people who sell there Ruger's used have to come down to attract buyers who might otherwise just spend a little more for a NIB gun. Maybe it's because Ruger doesn't have the catchet of brands like H&K and Sig. In any event, a solid Ruger centerfire will run practically forever.