I picked up an AR74 for dirt cheap and not too many 5.45x39 rounds in bulk locally.
I'm feeling pretty good about it as long as it doesn't blow up in my face.
While you can still find them, pick up a few firing assembly parts for the 74 ... a trigger and hammer spring would be the minimum to have in reserve. The 74 is usually remarkable durable.
You got in the game way late.
5.45 is really slim to none lately and for the foreseeable future. Sure some folks will dump it at shows and occasionally online, but I used to be able to get a spam can for $129/1080 rds.
Milady favours the 5,45 version over the 7,62, in her case a Romanian AIMS-74 with a folding stock. The recoil is a bit more noticeable with the *crutch* stock, which she prefers while on her motorbike or aboard the helicopter of which she's a charter pilot. The difference in flash at night is a consideration as well, she's tried the different shorty AR 15 versions in 5,56mm and was trained on the M16A2 when she was in the Air Force, so her decision is an informed and carefully chosen one- for her.
About the only way to really wreck an AK74 is to submerge it in water and forget to clear the chamber afterward; like an M16A1 the bore diameter is small enough that capillary action will keep the water in the bore unless the chamber is cleared to break the vacuum. Pop the round out of the chamber, point muzzle and flash hider toward ground to drain for a second, and chamber the next round in the magazine. Recover the ejected round, replace it in the magazine, and you're good to go.
The BATFE has forbidden import of any more 7N6 5,45mm military ammo, so pick up what you can when you see it...or use commercial hollowpoints instead.