Well (from my perspective) bronze is always beautiful !
The Nero is a common type reverse and I believe it is probably Lugdunum (Lyon) issue. If you scan through
ebay France this type crops up rather frequently and occasionally will sell for less but you are taking a chance when you go this route. Many sellers offer 'no returns' and this is a good reason why they can't get better prices. Nero is always popular and if you upgrade later on is fairly easy to trade.
Vitellius does not have much in the way of variety and this issue (from Tarraco) is the standard type. It took me almost 30 years before I found one I liked for a price I was willing to pay ! I paid less but yours has a better portrait and the name is quite boldly displayed. The reverse looks 'beveled' between 9-12 o'clock on the reverse. An illusion ?
The Titus is an interesting piece but it is a provincial (Alexandria ?) and a bit small at 21mm (although at 12.8 grams it has some heft !). I don't think you overpaid but I think an "imperial" type would fit in better with your theme. Still you can always trade up at a later date. Titus is always desirable.
The Domitian is 'okay' but on this one you may have been hasty. Again not that the price is bad but the coin is a bit corroded and you might feel it does not quite match up well with the others as far as its appearance. You did not break the bank of course and someday you will spot a better one and do the upgrade thing.
I hope you are not unhappy with my commentary as I believe in being honest. I acquired some VF/XF bronzes of Nero Titus and Domitian many years ago. I can't even afford what they sell for today !
But I did always try to be patient about finding these things. Which is one good reason I swore off of silver and gold 25 years ago. I knew I could never afford to buy everything and to be honest there are just too many fakes which are good enough to fool my trusting eye! At least with the bronze coinage I feel comfortable spotting the 'duds' and knowing that these are the real deal.
Even so modern technology is advancing so rapidly I wonder how long even this will last !
I personally don't go to many shows anymore and am stunned by the prices I see when I do go. The prices you paid seem to be in line with what they bring retail these days. The few coins I have been buying I buy on
ebay auctions. I win very few. But I think I enjoy the hunt as much as I enjoy actually buying them.