in EVE standard BPO price is roughly 10x that of the original item. but seeing as items in dust are quite cheap i would expect it to be 100x cost of the item per unit making dragonfly scout/assault bout 30mill for the bpo. BUT! that is because BPOs are readily available on the market. seeing as BPOs atm in DUST are limited in amount by how many Merc/Vet/Elite packs were bought. most people i know have 3 copies of the BPO from the merc packs. if all 4000 people online have that you're looking at max 12,000 Dragonfly scout BPOs slightly less for the assault, maybe 9000 as they came in later. Templar BPOs are based purely on how many Collectors editions were sold.
The only BPOs we can start working a price out are ones that are no longer available as they can't add any more so we have a fixed figure and work out a supply/demand kinda thing.
the dragonfly scouts will probably be the cheapest BPO seeing as many people have multiple copies whereas the Templar or Skinweaves will be most valuable as not many people received them also ones that recieve racial bonus will be worth more than the standard militia suits like skinweaves, eon, fossil, primordial and thale ect.

my guess is the Dren and Templar will be most desirable suits. both required high value purchases to receive them limiting who bought them and thus lowering the availability. it'd be nice for CCP to display the sales figures of each merc packs so we can tell how many of the bpos are out there.

As for weapons i'm going for the 'Daemon' shotgun BPO. its EUR only and seeing that the only way to get is via purchase of dust branded items (min -ú25) and the EUR playerbase is quite low. not many players will have received the Daemon. cheapest will be Exile. they're still readily available and many players received them in beta.