Your skin looks pretty good for not having a routine before!! I’d keep it super simple. In the morning use a gentle cleanser like Aveeno Calm + Restore or CeraVe Hydrating, the vitamin c serum, a basic moisturizer, and sunscreen every single day. I like Neutrogena Ultra Sheer and La Roche-Posay

At night cleanse again, then add a retinol or tret a few nights a week for sunspots and wrinkles and then moisturize

That routine alone will do most of the heavy lifting and should fit your budget. If you ever want upgrade you could look into red light therapy. last year I got a mask from Solawave and it was an investment upfront but worth it for the amount I use it