A couple years back I got some smooth Bulgarian polymer mags, with full metal reinforcement, K-var had them. They're actually nice mags with full reinforcement, but I've never seen them again. What were they? Think we will see them again? I'd like to get a few more if they ever come back.

5.45 or 7.62 mags?

Ah yes, I should have stated that. 7.62x39.

They had some slab sides with steel lug/lips for a short while. They were the perfect compromise between price and performance. To bad they never panned out.

Yep, those were the ones! I only got four, but I wish I would have picked up twenty of them! I think they were only 15-20 bucks a piece.

It wasn't these ? .... was it ?

I cannot attest to the accuracy of the CDNN description..."STEEL LINED POLY MAGAZINE".... nor does it say that the latch or front hook is steel lined...

http://www.cdnnsports.com/magazines/762x39-30-bk-poly-steel.html#.VG_acst0ycw

While those are decent mags (SIG ships them with 556Rs) they do not have steel lugs.

If you are talking about 'full metal reinforcement' not just locking-tabs and/or feed lips, then the ones that came from Bulgaria for the 7.62x39 are the 'Circle 10' model. Still available through K-var, can find them at CTD as well. Possible a few other places, they are distinct in their 'waffle like' look and have literally two circles around a '10'. So don't get fooled by knock-offs that cost $10 from Pro-Mag.

The cheapest I've seen them over the last year or so is around $40 per 30-round magazine.

Now if you are referring to the 'slab side' Bulgarian model, to my knowledge they have steel reinforced feed lips. Maybe locking tabs as well, but not 100% sure. They can still be found and typically run around the 10-20 $ range, but this is an indicator of what you are getting. They are NOT built to the same standard as the 'fully reinforced' Bulgarian waffle/circle-10 mags. But from what I've seen/read they seem to work pretty well. Personally I own 8x30 round and 2x40 round circle-10 magazines, they are damn good quality... I wish I would have bought more a few years back when they went for around $25-30...

Here are some links:
40 rounder (not fully-reinforced)
https://www.classicfirearms.com/bulgarian-polymer-ak-40-rd-mags

30 rounder (best quality, fully reinforces, probably the cheapest you will find for what this is right now)
http://www.cheaperthandirt.com/product/7-M47W

30 rounder (Russian Bakelite, sort of 'in-between' in terms of quality, is almost as 'reinforced' as the circle-10's but stops just a little short)
http://www.aimsurplus.com/product.aspx?item=MAK47I30&name=Russian+30rd+Bakelite+AK47+7.62x39+Rifle+Magazine&groupid=15

K-var of course still offers them, they offer good quality stuff. But I tend to look elsewhere when possible unless you like paying top-shelf prices:
http://www.k-var.com/shop/Circle-10-Magazines/