I would suggest a middle priced 200 for a life time pen. There are some very pretty ones. Then you can buy different nib widths for @ $30.
IMO, the 200's nib is one of the best made today....in it is vintage/semi-vintage narrow, it is a springy regular flex nib with a good ride.
I became very impressed with the 200's regular flex nib....'coming' from semi-flex, found it more and more a nice nib.In I had a slew of 400's didn't need a 200, so bought a 215 with the brass lined barrle, as a bit different from a 200.
I have in Pelikan semi-vintage '90's M400, 381 and a Celebry in 14 K nibs, a Celebry with a steel nib, a 215 and a Amethyst 200 also in steel. They are all = and good, be it gold or steel.
My W.Germany 200, has that slightly a tad, springier nib, the W. Germany Pelikan nibs are famous for...................if one nit picks, that W. Germany steel nib is better.
A regular flex nib is a bit dryer than semi-flex and will be a bit drier than fat and modern. That is great if you like shading ink. I like both M and F in regular flex. M is a good nib.........I picked up that prejudice here on the com too.....I was wrong as I later found out.
If you want as many 'noobies' do, butter smooth at any and all costs....you'd have to go to the fat and blobby 400/600 semi-nails...............rather boring in the long run. Nails and semi-nails tend to be if from a name company, butter smooth, in they don't have the give to make a good ride. A medium priced Waterman would have @ the same nib as a more expensive one.....a nail. The tipping would be the same.
I think looking for a cheap pen and a good nib set is the wrong way to go.....and I'd think 16 times about some cheap Knox nibs.
What to you want the nib to do?
The newer one is the less one would know.
Butter smooth nail/semi-nail. To be found everywhere in the companies don't have to repair so many nibs from Ham Fisted Ball Point Barbarians.
Good and smooth with good ride, regular flex.....and many older US makes were in this standard flex. Could be only the Pelikan 200 is that flex any more. Is a very good nib for shading inks.
Modern fat and blobby nibs are of course wetter, so would be lesser nibs if good shading is desired. Along with 90g or + laser paper, needed for shading inks.
German Semi-flex....for someone with 4-5 pens. Is stubbish and has good line variation. Semi-flex Oblique even more. Is a tad wet, due to ease of tine spread so has to be well matched with ink and paper to shade. German in they stubbed their semi-flex.
'40's Eversharp, some '50's Sheaffer and some English Swan pens can be found in semi-flex. I don't think they are stubs.
Stub semi-flex gives very good line variation.
Do not waste any money on any Oblique that is not German Semi-flex, in the line variation is too little....has to be hunted for. German semi-flex obliques are . My first semi-flex was a Pelikan 140 OB, and I couldn't have lucked out any better. The sweet spot was wide enough I didn't need to be so precise as with an OM or OF. It was sturdy enough, that it easily survived me....who was still Ham Fisted after a couple of years back to fountain pens. It helped lighten my hand, in it showed how hard I was pressing.
In Vintage and Semi-vintage B/OB is a writing nib......not a signature nib of modern fat nibs. More a fat M in today's widths. In semi-flex there is line variation from your normal writing pressures.
Pen's are like pistachios, can't eat just one. Can't cheap out either in the long run.
I spent a year of so wasting some of the money chasing $15-20-30 old cheap pens. Pen of the Week or Month in the mail Club.
Then slowly my border moved up to $50, and I got better pens. At $70 occasionally, I got fancy pens. I am now willing to spend $150 every six months on an old used pen. After a while one's collection become adequate as is, in one has much of what one wishes to collect. By me it's Pelikan, Geha and Osmia.
The prices I pay are less than half what good used pens cost in the States. So I can see why one would think buy a cheap body and put a medium valued nib on it.
You need to buy used. There are many vintage Parker, Esterbrook or Sheaffer pens that can be had at an affordable price.
For a nice used 200 and any semi-flex pen, look in German Ebay.....be aware the seller has to take paypal, or it will cost you $35 bank wire fee. We use bank wires over here instead of checks and inside the EU it is cheap. Second he will ship to the US? Some won't ship out of Germany, others refuse for political grounds to ship to today's USA. Someone told me that happen to him when trying to buy a pen from Portugal.