Hmm, let's see, I'm actually curious what the going rate would be. As a very, very general rule of thumb, companies in the service industries with few assets (think professional service consultancies like architecture firms, design firms, legal practices, accountants etc etc) typically sell for anywhere from 3X-5X EBITDA (earnings before interest, taxes, depreciation and amortization).
Acquiring a pilot career, in this case, would be somewhat similar. The seat you'd be buying has no actual assets, like most professional services firms that don't have many real assets and no inventory of goods. Instead, you're buying a profit flow (the annual compensation associated with that seat). You have to put in your own labor to realize that income stream, but the same applies if you, say, bought an accountancy practice.
So let's see. If we assume for a moment that the average widebody DAL CA clears, say, $450K/year, then the going price for that seat would be anywhere from $1.35M to $2.25M. This assumes of course that the purchaser is young enough to be able to occupy that seat for noticeably more than the 3-5 years required to recoup the initial investment.
By this logic a NBFO seat at mainline would retail for around $600K-$1M, assuming average NBFO comp of approx $200K.
And a regional FO seat would go for about $150-$250K.
Alrighty then. Any of you legacy 777 CAs want to retire early, hit me up

(Disclaimer: I am in no way an ERAU kid.)