That's true. But better HU does=more $$.
For a 500.00 budget I would consider the Sony CDX-M750 and the Nak CD-45Z. The pioneer 9200 should also be within that budget. Ubid has had the DEX-P1R and it has sold for under 400.00 recently. That is another very viable option.
The Sony CDX-C910 might be another good option if you would consider used equipment.