Alfatradiol is used topically and could be cheaper.
''In the treatment of androgenetic alopecia, the action mechanism of 17α-estradiol is to suppress 5α-reductase activity, which impedes the conversion of testosterone to the more potent metabolite DHT
5,
22,
23. In addition, it inhibits 17β-dehydrogenase activity, resulting in a slowing of the conversion process of androstenedione to testosterone. As a result, there is a reduction in the syntheses of testosterone and DHT
6. On the other hand, by stimulating aromatase, the conversion of testosterone to estradiol is accelerated, hence, testosterone is reduced. It thus acts to ultimately reduce DHT
7. In addition, it has been reported to accelerate the generation of hair follicular matrix cells
8.
The 0.025% Ell-Cranell® alpha solution has been used for the past 30 years in Europe and in South America. There were several reports about the therapeutic effects of 17α-estradiol in European population. In a controlled, randomized double-blind study, 63% of the treated patients with 17α-estradiol showed a reduction of the amount of telogen hairs, whereas in the control group the same reduction was found in only 37% of the cases
23. Wozel et al.
22 reported that 17α-estradiol increases and maintains the rate of anagen hair in 88% of the treated patients. When compared with minoxidil 17α-estradiol showed relatively lower efficacy compared to minoxidil in hair density and thickness
5.''
https://pmc.ncbi.nlm.nih.gov/articles/PMC3412238/#sec34