One wing is the same cost as seven packs. In total, you're giving up 35 packs worth of gold from the current expansion (or saving towards the next) for this adventure. I find that completely unreasonable if this is in addition to the regular expansions, rather than in place of one of them as these adventures were the last time they gave out new cards.
Even looking at the numbers you have, if it takes around a week to save up for a wing, that's a month and a week worth of gameplay in gold - and I'm assuming that's in gold that you get if you do every quest, nevermind if you aren't active enough and miss some. That, too, looks completely unreasonable to me for anyone who is relying mainly or entirely on gold to acquire their cards.