I recently replaced my original run flats with all season non- run flats: Goodrich Eagle GT from Discount Tires for about $600 for the set of 4. Running great so far...
I also replaced my trunk struts last week. Bought them on ebay for about $55 and my hubby changed them out in about 10 minutes. I would definitely recommend having another person there to help hold up the trunk while you're replacing them.