I've been using HC-110 for decades and never used Rodinal until a friend gave me a bottle last year. I'm pleasantly surprised. I still prefer replenished HC-110 . Old habits die hard.
That price is quite interesting. According to the information provided here, the price of Rodinal in 1927 was roughly the same as that of Adox Rodinal today - assuming the price in the ad refers to one litre of 1+50 working solution. As mentioned in that thread, one would of course have to factor in the cost of goods and typical wages in 1927, in order to come to a meaningful comparison.