I don't have a recommendation for online and I know I'm going against what you said about not being able to afford private, but I wanted to share something you might not have thought of...
community college!
I got 3+ years of PRIVATE classical voice lessons at a community college for $55 per semester hour. I think they were 2 hours per semester for private lessons. met 1X per week, hour per week for ~4 months per semester. so for $110 per semester I got about 15 weeks of lessons. that's less than $8 / week.
(I think I was about 45 years old, give or take at the time)
community college! excellent resource.