Did you receive the inquiry via email or via Sedo's bid system?
Domains like these are definitely being sought after by end users, it's unlikely but not entirely that a reseller is making offers on it.
These type of end users can definitely offer a better price for your domains and in this case $500 is too low in my opinion.
Reg fee isn't a problem for you regarding these two domains since it's only two lunches for you to renew so take this in mind, you have now received an offer from most likely a end user that wants to use these domains to promote their services so this is a good sign.
The domains are very descriptive and on point and desirable by many business owners involved with financing, if you would scare this potential buyer away would this mean you could never find a buyer for it again?
I don't think so personally, there is a another buyer potentially interested in these two domains in the future.
You have parked it now and it resulted in a inquiry, can you imagine what could happen if you actively send out emails to every business involved with financing located in that region?
You got it

more potential interested buyers.
So what could you get for the pair is what you might be thinking? Always a though question but i am sure when more interested parties are involved with these domains you could definitely yield better results.
So start sending out emails from the email address of the domains that you of course already have set up with your personal name and ending in @VancouverFinancing.com and the other one for the other region and contact businesses involved with financing in these regions.
This way you can increase the chances to attract more buyers and receive better offers for the two domains individually even.
If you need the money you're in a though position since then it can be tempting especially if you need the money fast but if you don't have this dilemma i would definitely hold out thus wait to sell and tell the bidder that $500 for the pair is not convincing to make you a seller.
Be polite and professional and give them a high counter offer for each individual domain.
Regional keywords with keywords that refer to high value business can yield some nice sales such as PasadenaRealEstate.com that sold for $44,187.
These are industries where high amounts of money are involved so i would definitely would not sell for $500, i mean Vancouver and Ontario aren't small towns in the middle of nowhere
Regarding the counter offer, just counter for 25k each and let it play out if the ball is still in play after you made such an offer and start sending out emails at the same time to all the companies you can find located in this region.
So what if you scared them off if they don't respond anymore, you got two nice domains that are worth more the current offer you gotten from them and you will sell them eventually and the reg fee is negligible.
Just my 2 cents.
Sorry for the long post.