Other suggestion:

http://backpack.tf/vote/id/54837bd9ba8d88d5638b49ae

Classifieds at time of posting:

x1 at 8 refined

x1 at 12 refined

x2 at 1 key

x1 at 20 refined

x1 at 1 key

Rest of them are killstreak.

SCM:

http://steamcommunity.com/market/listings/440/Strange%20Soda%20Popper

Sellers at $1.17 to $1.25 - ~6.5 refined

Sellers/Solds:

http://www.tf2outpost.com/trade/23704018 - Offered "My Festive Spec KS Wrench worth 2 key, An australium gold football helmet, and 5 ref for the soda popper"

http://www.tf2outpost.com/trade/23896216 - 1 key and 7 ref with parts and name tag.

http://www.tf2outpost.com/trade/23021931 - Offered 6 keys for Strange Huntsman and Strange Soda popper.

http://www.tf2outpost.com/trade/23910962 - 1 key

http://www.tf2outpost.com/trade/24014207 - CS:GO knives

http://www.tf2outpost.com/trade/23959915 - CS:GO Skins

http://www.tf2outpost.com/trade/18928698 - Sold for 1 key 4 ref

http://www.tf2outpost.com/trade/23995185 - Added for soda popper, no price specified

http://bazaar.tf/trade/1117379 - No price specified

http://bazaar.tf/trade/1071959 - Taking offers, no price specified

Buyers:

http://bazaar.tf/trade/783785 - buying for 6.00

http://www.tf2outpost.com/trade/23998160 - buying for 4.00

http://bazaar.tf/trade/566441 - buying for 4.00 "bp.tf prices"

http://www.tf2outpost.com/trade/23968759 - buying for 4.00

http://www.tf2outpost.com/trade/24009277 - buying for 4.00

http://www.tf2outpost.com/trade/23969516 - buying for 4.00 "bp.tf prices"

http://www.tf2outpost.com/trade/23951180 - buying for 3.77

http://bazaar.tf/trade/1008057 - buying for 3.77

http://www.tf2outpost.com/trade/24018560 - buying for 3.66

http://www.tf2outpost.com/trade/24009139 - buying for 3.66

http://www.tf2outpost.com/trade/23867183 - buying for 3.66

http://www.tf2outpost.com/trade/23757614 - buying for 3.66

http://www.tf2outpost.com/trade/23329974 - buying for 3.55

http://www.tf2outpost.com/trade/23919773 - buying for 3.55

http://www.tf2outpost.com/trade/23962029 - buying for 3.55

http://www.tf2outpost.com/trade/23129440 - buying for 3.44

http://www.tf2outpost.com/trade/23822466 - buying for 3.44

http://www.tf2outpost.com/trade/22747669 - buying for 3.33

http://bazaar.tf/trade/1081808 - buying for 3.33

http://bazaar.tf/trade/348817 - buying for 3.33 [BOT]

http://www.tf2outpost.com/trade/24017777 - buying for 3.11

http://www.tf2outpost.com/trade/23838787 - buying for 3.00

http://www.tf2outpost.com/trade/17303675 - buying for 3.00

http://bazaar.tf/trade/852553 - "I buy items with discount"

http://bazaar.tf/trade/403603 - "Offer me your prices"

Conclusion

Lots of people are buying this within 3-4 refined, but only one or two of them have actually had offers. Compared to the people selling them for 1 key, they have tons of offers on theirs. There are little sellers because most of these have parts, name tags, killstreaks, etc.