Flea market is locked behind level 20, so you will have to relay on traders for some time before you will be able to buy what you want. Here is what I propose to use till you will have freedom of choice again.
CLASS 2 ARMOR
I would always try to use class 2 armor. It's for protection from scavs only. Best one is Paca.")
CLASS 3 ARMOR
SB5-16 "Uley" is the only armor you can buy for money and it's also the best one to use.
Kirasa is on par with "Uley" when it comes to effective durability. Problem is it's made of combained materials, so it will lose durability faster when you repair it. Press armor is decent if you will find one.") SB23-1 and UNTAR offer the same protection level, so go with camo one when on the budget.
CLASS 4 ARMOR
Best available option is SB3TM. Ceramic armors you can buy will lose maximum durability very fast and offer very low protection.
SSh-68 is a very good helmet with high ricochet chance. If you have extra money then Ratnik is an upgrade that offers ears protection.
VPO-136 uses best penetration round early game. It's AK base, so you can also mod it a little with basic traders. Later options for full auto guns.
I don't have slide for SKS, but it's a very decent early game gun if you don't mind it's iron sight. If you want to snipe then use OP-SKS with PSO scope.
ADAR has decent stats and good penetration round early game. VPO-209 is another gun with very good round early game. It's also AK base, so you can put reflex sight on it, if you wish so. 5.45 AKs are another great option. AKS-74U is not the best, but it can work. Option to go full auto and good penetration rounds is what makes AKs shine early game. You will be able to find a lot of BT rounds on all maps, especially on Reserve. Prapor also offer two good barters for BP and BT rounds. Early smgs can be a very good option too. PST gzh round can go through class 3 armors. Class 4 is a problem, but becasue recoil is quite low on SMGs, you should have easier time to pop heads when spraying.
LEG META SMGs
Leg meta means shooting somebody in legs to kill them. Best choice for the job is PPSH-41 with LRN or LRNPC rounds. Your other leg meta options. Second best is Kedr with PSV round. MP7 will be probably hard to get early. MP5 Kurz has extra recoil. Vector and MP9 are your later options.
Early shotgun options for you leg meta sweet dreams. Best shotty is MP-153, it can shot a little faster than other options. Early you can use either 7mm or Express. With Workbench lvl1 or Jaeger LL2 you can get your hands on Magnum buckshot that can one-tap through stomach.
I treat pistols as ultra budget option. I prefer 9x19mm ones, becasue with PST gzh round you have some chance against Paca. Best one is probably Beretta, but if you want to pay a little extra then you can go with Glock17. Pistols are only great if you can land those headshots.
Mosin is great equalizer when you notice people running with class 4 armor on regular basis. It shots slow and you need 2 thorax shots to kill, but it's always an option.
Another option is RFB, you can buy it with M80 rounds from Peacekeeper at LL2. It's semi auto gun with decent stats, great option to melt people using those pesky class 4 and budget class 5 armors!
Other option is Vepr Hunter from Jaeger LL2.
TARKOV ARMOR CALCULATOR: