It's true the value of codes have swung wildly over the 2 years they've been around. I remember they hay day of codes when you only got them from packs from hobby stores, and they were selling for $1 each, and naturally when the game had been down for 3-4 months with still a few months more of waiting the prices fell to $0.10-$0.15.
Before the new year the codes were solid at $0.20-$0.25, however ever since the announcement of old codes eventually being limited to opening only digital packs of which they came, the price has gone back up to $0.30. Sure you have sellers still that drop in with a couple dozen codes, or maybe 100 at $0.25, just like you have buyers posting threads offering $0.40 even though I'm selling for $0,30 right here.
I'm not interested in dropping my price right now because I have been moving through codes very quickly. Why drop the price when there is demand? I wouldn't be surprised if the price continues to rise.
Don't get me wrong, your offer was fair and I thought about taking it or countering even. However the amount of time I've put into gathering all these codes in to one place along with verifying them and scanning them (into text), I feel its fair where its at.
Hopefully I answered your question =)