There are lots of "deals" out there.
I do ride a 40+ year old Colnago. But, it has also had a few updates over the years. I got to ride Dad's old bike which hasn't been upgraded last Christmas, and it just felt a bit clunky.
Most of the racing bikes from yester-year had a low gear of 42/21 or 42/23... and were fine for hills. It is still amazing at how many threads I see about people wishing to add a 32T pie plate to their bike... or wondering if a 30T front sprocket is low enough.
But, a few extra gears can be nice
Even with classic friction shifting, I believe it is easier with 8+ rear sprockets.
I do believe that today's low-end bikes are just about as good as the high-end bikes from a couple of decades ago.
Gone are the 35 pound Schwinns.... Most low to mid range road bikes today are 20 to 25 lbs... a good target range for the classics. More gears. Better shifting, better braking. More solid rims.... Sewups???
As far as finding the deals... You don't have to try to find a $5000 CF bike for $300. But there are lots of good deals on previously $1000 to $1500 bikes (or so) in the $300 range.
Perhaps the best deals are on those bikes that require a bit of work. And if one is willing to do the work, then the deals are out there. Perhaps a bike with a mangled rim, or having had a few parts stripped.
One might not expect a Newbie to do huge amounts of customization... but perhaps some youngsters are more willing to experiment than one might give them credit for.
I just snagged a $50 Jamis Coda Hybrid. It is more advanced than one might expect. I'm not quite sure what will become of it. Perhaps it will end up with an additional $100 or so to make it into a sweet chromoly cyclocross bike.