Use Single Table Or Multiple Separate Tables?

Hi,

We are building an application for online system for people to place ADs for selling various used items like Car, Electronics, Houses, Books etc.

If someone selling a car then he can fill out headline, year, make, model, mileage, transmission, condition, color, price, description, contact etc.

Similarly if someone selling a digital camera he will fillout headline, memory, zoom, megapixel, maker, model, color, batter, description etc.

Option 1: I can have a main table to hold the common attributes of all different types of ADs (headline, images, contact, price, color, condition, description)

+ 1 table to store string values of all ADs (car: maker, model, square feet (if house), memory, megapixel (camera) etc)

+ 1 table to store the droplist select values(car: transmission, door, seat etc; house: year_built)

pros: single table for all ADs. unique IDs for all ADs, easy to extend as new attributes can be dropped easily.

cons: lot of physical reads of 2nd and 3rd table from join. 10 times physical reads compared to option 2 when reading 5000 records.

Option 2: have different set of table for each AD type. Car will have its own main table + 1 table to store multiselect list box values.

Similarly housing will have its own set of tables

pros: 10% less physical read than option 1.

cons: hard to add new attributes. We have to modify the main table by adding one column.

Query will go to different table based on the category.

Do you have any suggestions on which way to go?Thanks