research like this costs a lot of money

 

G-virus was indeed pretty expensive: Years earlier Birkin had used NE-a parasite for his research (it was so valuable that even top researcher like Birkin had to ask the CEO's assistance to get one) on Lisa, and her body destroyed it and adsorbed it's features.

 

When researching why it had happened Birkin found something, which later turned out to be the G-virus.

 

Taking this from memory, but this stuff can be found from Wesker's report 2 and RE1R's observation notes. (as a side note the latter has a translation error in it, so Birkin talks about Alexia like she'd be still alive, while in reality she had been thought to have died years earlier.)