Totally agree with flu. Carmel Valley, even condo doesn’t cash flow well. If your budget is $400-500k and want to be around UCSD, I’d recommend SFR in Mira Mesa. They’re currently going for $430-500k depending on condition. Lets take the average of $460k, mortgage would be $1900/month, assuming you’re loaning it as an investment property @ 4.75%. If you’re loaning it as a 2nd home @ 4.125%, your payment would be $1780/month. Tax would be $420/month and insurance would be ~$50/month. So, your PITI would be $2250-2370/month. Those houses are renting for $2200-2300/month today.
But if you prefer condo/townhouse, I would consider UTC area instead. It’s much more convenient to commute to UCSD in UTC. there are shuttles around UTC area that will take your kid to UCSD.