Filter subform with combo box and select specific records

[socasteel21 via AccessMonster.com]

I have an purchase order form for construction equipment. I would like to be
able to enter a model number of a machine using a combo box, which would then
filter a subform by all options available for that particular model. After
this is done, I need to be able to move to the subform and check a box on any
combination of records (these records include a price for each option). I
then need a box outside of the subform to total the price for all of the
selected records. I need all of this information to be stored in a table so
that I may look up old purchase orders.

Any help would be greatly appreciated.

Thanks in advance,

Shannan