car fridge alternative

hello, as i find myself going more and more outdoors these days i have though about getting a car fridge. I read a lot of Q&A's in this forum and realise that it would be a worthwhile investment. i'm be looking at something in the 60-70L size but the relatively high cost has made me think about the following alternative, i really welcome any thoughts, comments suggestions from people who may have seen this in their travels or have set it up themselves.

basically i thought about getting a small 240V bar fridge. these cost around $200 (65-70Lsize) for new units from shops or even less much less for new/ as new units in the trading post. Then getting a 200-300W inverter to power it. The inverter would cost a furhter $200-$250 making the total around $400, which is considerably lower then most 60-70L car fridges that i've seen so far.

further for those who like the hands on approach, i considered making the inverter from an old dissused computer UPS (Uninterupted Power Supply) module. These basically run off a built in 12V lead acid battery, and once the battery has died the system is usually useless. one then throws out the battery and connects the UPS to the cars AUX battery. this way i would have a inverter which costs around $20, which is the cost of the old UPS module, and one which gives atleast 500W.

this way i have a car fridge as well as a decent inverter for a fraction of the cost.

look forward to any feedback on this setup or why a proper car fridge would be so much better.