Daily usage Cialis available on prescription?

I've had ED problems for decades - after falling off a horse and compressing the nerves in my lower back, (I'm 59 years old now, in very good physical shape etc).  But Cialis always works to get a solid erection, although I have no sensitivity and find it hard to achieve an orgasm. Viagra also works well, but again zero sensitivity and zero orgasm. (I can achieve orgasm when not using Cialis or Viagra - but it is damn hard work to try to get the old pecker stiff!!)

I've read that a daily dose (lower amount of the medication) of Cialis can also be taken, to enable one to 'perform on cue' without needing to take some Cialis an hour or so prior to sexual activity.

The recommended dose seems to be a quarter of a tablet.

Genuine Ciasis is about 400 baht per tab.  So this daily dosage would be about 3,000 baht a month.

Is there anyway to reduce that cost by being prescribed daily Cialis by a doctor?  Additionally, what are the recommended pharmacies in Bangkok (Sukhumvit) or Pattaya where I can be sure that I am purchasing genuine Cialis?