Cheap, yeah. More cost effective... probably not except for the Airborne/SSB variants.
An 'schreck will hit 92% of the time at 250m. An non-airborne bazooka, 58% at 200m. Non-airborne PIAT, 42%. In terms of price versus first shot hit chance at maximum range divided by price, they're almost identical, with a slight lead for the Panzershreck and the PIAT at the bottom of the pack. Shorter ranges favor the less accurate weapons, as does vet, so in general they're probably all pretty close with regards how much your point investment leads to landing that first hit.
(accuracy values derived from
https://www.reddit.com/r/Steel_Divi...lculations_explained/?st=j8g95w34&sh=805fe786)
Overall, the best RPG teams are probably the Allied airborne PIAT, airborne Bazooka, and Commando Tank buster teams. The worst of them, the PIAT, is still a Bazooka with +1 accuracy and it gets better from there.
In second place, IMHO, is the Panzershreck despite that price tag. 50m extra range, best hit-to-cost ratio, some chance of hitting even when suppressed (but lower ROF), and the fact that it almost always hits means that you can buy one and know it reliably can kill a target that gets in range. This spares you the ugly decision of buying one and potentially missing and having an armored vehicle running free in your lines, or needing to buy two to reliably accomplish what a single 'shreck does reliably.
The non-Airborne Bazooka's in third place, though, and it's not chopped liver. It's got almost as good chance of hitting on the first hit relative to it's price and lower price investment so you can have more stuff.
In fourth place, non-Airborne PIAT. Worst hit-to-cost ratio and it even has AP 4 instead of AP 6, which presumably translates to less chance of accomplishing something when it does hit. It is the cheapest of the lot, but you're generally giving up way more than you're gaining even if you buy two of them to compensate.
By and large, the various AT teams are all pretty all right, except for the PIAT.
EDIT-
ZhukoDim suggests that all of my accuracy values are one row above where they ought to be in that results table. The examples in the linked URL seem to back him on that.
The impact of this is that 'shrecks are better than I thought they were, and PIATs worse, mostly. This doesn't change my final conclusions much, except that it ambiguates where I think some of the allied airborne RPG teams fall in relation to the 'shreck.