Every member of the military forces not salaried as such shall receive from the state, while engaged in any service ordered by the governor, pay and allowances at the rate paid or allowed by law to members of similar rank and length of service in the regular Army or regular Air Force of the United States, as the case may be, but no such member shall receive less than twenty dollars per day. Subject to available appropriations, after a member of the military forces has been engaged in service pursuant to this section for a period of more than thirty consecutive days, the member shall be eligible to enroll in any benefit plan created for employees of the state, including but not limited to state employee group benefits pursuant to part 6 of article 50 of title 24, C.R.S., and the public employees' retirement association created pursuant to article 51 of title 24, C.R.S.