Any PHD worth doing will be funded (typically, it means you get full tuition + a stipend to help pay for your rent/food.)
So, rather than dividing costs between undergrad and grad, your parents could invest into undergrad only. Talk to them and see if they’re willing to pay 50K/year (if they intended on paying 30K for undergrad + PHD, it means 240K set aside for your studies?)
Beside Penn, good schools for Physics include Haverford (need only), Harvey Mudd (need), CalTech, and Lawrence (merit).
UArizona and ASU (with Barrett) are strong in your field of interest and you’d likely qualify for their Honors College so you’re lucky to be living in AZ. Look into Lawrence: would you be more interested in this college than in UAZ?