db schema question

I'm building a product catalog database with MySQL and I'm wondering if there is a more efficent way to create my tables.
Here's the structure:

product
----------
product_id
product_name
product_desc

size
-----
size_id
size

color
-----
color_id
color

price
-----
price_id
price

quantity
-----
quantity_id
quantity

map_price
-------------
map_price_id
product_id
price_id
quantity_id

map_size
------------
map_size_id
product_id
size_id

map_color
---------------
map_color_id
product_id
color_id

There are obviously more tables and more information in the db, but this all that is required to answer my question.

So the relationship is, one product can have many sizes and colors, it is possible for a product to have zero sizes and colors. Size and color are not related.

One product can also have up to 5 prices and quantities, price and quantity are related so that a quantity of 100 is $4.00 while a quantity of 500 is $3.80. However, this does not hold true for every product. For example, another product with a quantity of 500 might be $6.00.

In this application, quantity is based on price, the users are buying the products in bulk, so for every x increase in quantity, the price will go down. Unfortunately there is no pattern between the price / quantity relationship, so I can't apply an equation to figure the pricing.

I have set up mapping tables that relate the color, size, price and quantity to one product. My question is: is there a way that is just as efficent to minimize the number of mapping tables? Since size and color are not related, I can't think of a way to combine those tables. Perhaps not in this schema, but definitely in others I end up with about 5-6 mapping tables and 5-6 two-field tables like the color and size table above. This seems like a flawed design, although the data is normalized, I end up with a lot of tables.