I lost my rothenburgen years ago and bought a cheap wickes one for solder a couple of joints.
Yes, it takes longer to warm up the joint and yes, you need a lighter to start the flame.
But if you (like me) do a few joints a couple of times a year, that's absolutely fine.
I've had the same gas bottle for the past 5 years, that tell you how often I use it.
I have two here, one of which as the brass regulator. One of the bonuses was that no matter which way you oriented it, the flame remained the same. With cheap gas blow lamps, you get the flaring as gas turns to liquid coming through the jet..