We need photos of the plane to get any idea on value. Condition is
everything when it comes to price, and it gets confusing since you
described it as a Bailey plane rather than as a Stanley.
Leonard Bailey perfected the modern metal plane and sold many under
his own name until Stanley purchased his patents in the late 1800s.
Stanley then used the Bailey name on their planes for several decades.
So there are Bailey and Stanley+Bailey planes.
https://virginiatoolworks.com/2012/04/23/stanley-vs-bailey-a-short-history/
If he's selling a rare non-Stanley Bailey No. 8 plane, then it's likely worth
some serious money. If it's a Stanley plane with the name Bailey on it, then
it's likely a relatively common No. 8 jointer plane and worth $50 to $200
depending on condition. The true "creme de la creme" of jointer planes is
a Stanley "Bedrock" No. 608 in perfect condition dating from the 1920s
or 1930s. Lie Nelson Toolworks make an improved copy of this plane for
a mere $475...
https://www.lie-nielsen.com/product/standard-bench-planes/no.-8-jointer-plane?node=4171
Geeky collector issues aside, if his No. 8 has original rosewood handles
and is in good working condition, then it will make a nice "user" plane.
Old Stanley planes made in America before 1950 always work better
than new planes made in Asia sold at hardware stores nowadays.
As for the Russell Jennings bits, they're common and you can still find NOS
sets from tool dealers. To give you some idea on pricing for like-new set,
this fellow is usually a bit higher than typical market price...
http://www.jimbodetools.com/Complet...Bits-in-its-Original-3-Tiered-Box-p48160.html
I think I paid about $125 for a similar NOS box set a couple years ago.
Most of my bits were still wrapped in the original paper.
Your guy is selling a "user quality" set, so I'd pass if bits are missing, the
cutting spurs have no remaining life, or if it's a mixed set of brands (Russell
Jennings, Stanley, Irwins, GreenLee). On the other hand, at the right price
(around $30), this is a good first set you can use to practice sharpening...
http://www.fine-tools.com/G-augerbitfile.html
Russell Jennings, Stanley / Russell Jennings, Irwin, GreenLee, etc. all work
about the same if they're sharp. Old vs. new work the same, so long as they
fit your brace and are sharp.
Trivia: The common Russell Jennings No. 100 bits had a double-thread on
the lead screw which looks fine but is actually coarse in use. The more rare
No. 101 bits had a single-thread lead screw like Irwin, etc. which looks more
coarse. Either type works fine.