Your Toyota dealer probably suggested to replace the bumper because of the weakness caused by the accident ( crack,etc) that you can not see. I have scrape the bottom valances of my 2003 xrs often enough especialy around speed bumps and killer sidewalk that have to much slope here in Montreal. But I have replaced the parts succesfully with parts ordered from the following site:
http://www.partstrain.com/ . They are very cheap and the parts are of OEM quality.
You can get them painted at your local bodyshop. I remove the front valances for winter.
A driver side bottom front valance is $381.00 CDN from a dealer compared to $128.00 US.