I would pick a 54r rifle if it could be bought at a good price. I am sure you realize the days of reasonably priced 54r rifles like the romy psl are long gone.
If I remember correctly the psl mags are now $50+ when you can find them. I hope Kalashnikov USA will make a 54r rifle some day. Let us know what you decide
to do.
AKM I was looking at will probably come out to 1200 with shipping and transfer.
Mags are covered, but for comparison, lets use the same amount, which would come out to 10 BHO mags for about $175.....or $225 if I go with modified polymers.
Probably update furniture, because I'm really digging the zhukov stock and moe handguard, so it will run me about $150, if I can find those prices again.
I like to have about 5,000 rounds minimum per rifle, but no less than 1,000 stocked away, so lets say 2,000 rounds initially, which should be about $600 on a good day.
Optics can come later; not essential at the moment.
Total for AKM: $2125 including ammo w/ steel mags, $2175 w/ polymer mags.
The 54R I'm looking at is sub $1000, but add on the transfer fee and shipping it's now 1100.
Given that this will be a DMR, will definitely need a scope and mount; probably another 500 minimum.
Couple that with the OEM 5 round mags, which run about $75/pair plus shipping, so lets say $125 a pair to be safe. Multiply that by 5 (to have a standard load out capacity plus extras in case) and you are looking at $625 in mags alone.
For DMRs, I like to have about 2000 rounds, but a bare minimum of 1000. ammo is about $16/20 rounds at the moment, so it might be around $400/500, so lets double that to $800/1000
Total for 54R (using highest values) :

$3025

Of course....I could just just replace the AKM I was looking at with a WASR and save like 500 bucks

Look at these prices, the WASR is looking mighty tempting and makes me want to reconsider

But then again....these Prices are assuming I'm starting with nothing, where as I have certain things covered for either the AKM or 54R.