$500 seems too low to me; I'd be looking to sell for ~$2-3k (some insurance sales below):
Domain TLD SalePrice SaleDate SaleThru
JupiterInsurance com $800 Dec 07 Sedo
RenewInsurance com $4,000 Dec 07 Private
InsuranceAuthority com $3,388 Dec 07 Afternic
InsuranceLawyers com $10,000 Nov 07 Moniker/Traffic
InsuranceBoston com $1,000 Oct 07 TDNam
DelawareInsurance com $12,000 Oct 07 Moniker/Traffic
IndentityInsurance com $75 Aug 07 Afternic
InsuranceGeneral com $2,000 Aug 07 BuyDomains
InsuranceMatters com $3,366 Aug 07 BuyDomains
FederalInsurance com $5,250 Aug 07 Afternic/BuyDomains
SoutheastInsurance com $3,177 Jul 07 BuyDomains
HurricaneInsurance com $10,000 Jul 07 Sedo
WealthInsurance com $2,000 Jul 07 BuyDomains
InsuranceFund com $1,180 Jun 07 Moniker/Traffic
UKInsurance com $21,967 Jun 07 Moniker/Traffic
DiscountInsurance com $60,000 Jun 07 Moniker/Traffic
InsuranceInstant com $60 May 07 Sedo Auction
BeyondInsurance com $4,400 May 07 Sedo
InsurancePlease com $1,400 May 07 Afternic
InsuranceGuru com $1,800 Apr 07 Afternic
InsuranceKnowledge com $2,288 Apr 07 BuyDomains
DIYInsurance com $2,150 Apr 07 BuyDomains
AnimalInsurance com $2,800 Mar 07 BuyDomains
InsuranceAssociates com $4,000 Mar 07 BuyDomains
TeenInsurance com $3,833 Mar 07 BuyDomains
WeatherInsurance com $3,000 Mar 07 BuyDomains
InvestmentInsurance com $2,688 Mar 07 Afternic
InsuranceLoans com $6,000 Mar 07 Moniker/Traffic
InsuranceRange com $81 Feb 07 Sedo Auction
TradeInsurance com $3,548 Feb 07 Sedo
InsuranceAuctions com $2,200 Feb 07 BuyDomains
GeoInsurance com $2,000 Jan 07 BuyDomains
NycInsurance com $2,150 Dec 06 SnapNames
CenturyInsurance com $7,100 Dec 06 SnapNames
SpecialtyInsurance com $6,600 Dec 06 SnapNames
DamageInsurance com $1,050 Dec 06 Afternic
MbInsurance com $2,000 Dec 06 BuyDomains
InsuranceOne com $2,600 Oct 06 SnapNames
InsuranceEstimates com $4,088 Oct 06 SnapNames
FairwayInsurance com $900 Oct 06 Sedo
(see DnSalePrice.com for add'l insurance sales)