User own Permission

I suppose one could add a field like user/owner that could then be able to modify the rooms they create by using http://drupal.org/project/nodeaccess_userreference (or see similar module linked from this module)

but I believe it would make life easier if there was permissions like
Create BOOKABLEUNITNAME bookable unit (for all bookable unit types)
edit own bookable unit

of course a USER id has to associate each bookable unit to a user

What would be really great is havnig the option to add an "owner", that is a reference to an user, which is (can be) then assigned the permissions to administer any rooms they own including their availability and prices, manage bookings for those rooms,...
A great improvement in scenarios where there is more than one person in charge for administration of rooms...
or is there an easier way?
Since there are already seperate permissions for rooms unit to assign permisions on per unit type basis that is great, the only missing part is the same thing for managing availability and prices.
since now as soon as one gets the permission to "manage availability" he can change availability also to units without the permision to administer them (and that is a problem when displaying the "bulk availability manager")
any ideas?
GiorgosK, were you able to make it work by using nodeaccess userreference? i failed rather early with that idea.

@flynorc
yes I also failed, the idea was correct but the module is "node" access so it does not work with rooms which is entity

if there is an entity based access control probably it will work

I tried solving the problem by adding a field owner to booking unit types that is a user reference to the people who are allowed to change the availability and other information and then modifying the queries that display the units in bulk availability/pricing manager, searching for availability, editing room details,...

i guess the better way would be to modify the permissions in a way that would add this field by default and then add a permission to be able to modify the units and manage availability/pricing for "own" units -> similar to the way the permission for edit own content works with content types.