The o.p. is also confusing bcd (bolt circle diameter) (110mm) with spindle length (unknown), and, as Bob says 73mm is not a recognized standard BB length for roadbikes. Not that it matters! Bottom bracket spindles are available in a dizzying variety of shell lengths and spindle lengths and something can be found that will fit (and for a lot less than 100 euros) if the o.p. can determine exactly what they need.

Edit: it would appear that Tiagra cranksets need HollowTech II bottom bracket cups. I assume you already have a spindle? (24mm)
https://www.universalcycles.com/shop...0&category=347