Not sure if it's just me, but I had absolutely no trouble going through the checkout process and just finished installing several of the apps. I was never asked for a serial number for Photoshop - it seems to be baked in if you install through their installer and log in with your Adobe ID. (Also, paying $30 per month vs $1900+ up front seems to be a hell of a deal.)
$1900 (which version?) Are you buying new or upgrading? Checking their website the upgrade is only $525. As they only come out with a new version about once every 2 years that. $525 to upgrade vs $720 for a 2 year subscription. Even if you were purchasing new it's still cheaper to pay outright. 6 years at $30 a month for the first year + $50 for the next 5 is $3360 1900 + 2 upgrades at 525 is $2950
Even if I decide to keep the subscription after the project is over, paying just $400 more over 6 years for the benefit of amortizing my business expenses, not having to worry about being out of date, and not having to predict ahead of time which tools I will need in the future (e.g. if I had purchased the Web Suite a year ago, I wouldn't get After Effects) is totally worth it (to me).