I missed these questions earlier on, sorry
My Luxor-made Frontier is actually made to slightly better quality than the UK-made model of that pen was.
The UK pens had a rubber coating on their grip-section, and that used to fall off in patches. I had to scrape it off my own UK Frontier.
The Frontier was made in the UK at a time when the company was losing lots of money, so its quality suffered as production costs were cut drastically. The company got bought out, and the UK factory got closed down, at the end of the era during which Frontiers were made here.
My two Luxor Frontiers are well-made and they have good nibs, but their caps don’t ‘post’ very well on to the back of the pen when writing with them. I think that this is a design problem, rather than a manufacturing problem.
My all-steel Luxor Vector is really well made. In this all-steel version it is a tough pen, and it would be a great pen for school or university if one finds its size comfortable.
My 25 is from the 1970s, and it is made to a higher standard than my early-2000s Jotter (again, this is the era when Parker was cutting costs).
All my 45s are from the 1970s, and they are all well-made, but their caps don’t ‘post’ as well as that of the 25 or the Vector; both of which are shaped so that the cap slots firmly on to the slightly-narrower end of the pen’s body.
The Urban is a heavier pen, made out of brass. Its cap ‘posts’ well, but its weight then makes the pen feel unbalanced.
The Jotter, Vector, and Urban all use the same nibs. They are very stiff, but they write reliably. The Frontier nibs are very slightly ‘bouncy’. The 45 steel nibs are very stiff, but reliable. My UK-made 14k gold 45 nib is slightly ‘bouncy’ too.
The 25 is probably the pen that I find to be most-comfortable in my hand when writing.
The Urban is the prettiest, and when I use it I do enjoy using it.
The Vector is a great tough pen to take out on-site, or to use in e.g. school, but it is a tiny bit too-narrow for me to use it comfortably for a long writing session. The Jotter is also a little bit small for my hand.
The narrow, tapered shape of the 45 means that I take a little while to get used to it (I normally use wider pens), but the nibs on mine write with quite narrow lines, so they make great pens for writing postcards in permanent black ink.
As for your price question, €28 for a gold-nibbed all-steel 45 would be a decent price here in the UK.
Is it a 14k gold nib? Or is it a gold-plated steel nib?
What era does the pen date-to?
And what size/grind is the nib?
45s were made with everything from XF to B, and with Italics, and obliques, and reverse-obliques. There should be a letter stamped in the underside of the nib collar. One of the more-‘exotic’ nibs might not suit your handwriting, so it is a good idea to check what size/grind of nib is on the pen.