Please help - fix DVD drive issue or what external drive to buy

My imac 10.6.8 suddenly stopped reading dvd rom disks last night without any warning. I was playing Sims 3 with my daughter and when we went to start the game up the disk would act like it was going to load but just spit out after a few seconds. I tried some other disks like spore or the sims expansions and the same thing happend BUT when I tried regular cd types (like cd-r) they load fine. I reset the PRAM and verified permissions, I sprayed electronic air cleaner into the slot - no luck. I don't have the money to have it looked (warrantees over) at and am not savvy enough to try to fix anything myself.
Is there some other fix i could try (I can follow simple directions but don't know much at all about whats going on with the system) Or could you help me find a inexpensive external drive. I need one thats pretty much plug n play and that'll be able to run games like sims 3.
My daughter is so sad, she wants to play over her holiday break but it's just not looking good for us. Please help if you can, I am sorry this is so long - I'm a bit long winded
Here's some of my computer info... I'm not sure what you'd need to know so I'm just going to copy paste it all.
Model Identifier: iMac11,1 Processor Name: Intel Core i5 Processor Speed: 2.66 GHz Number Of Processors: 1 Total Number Of Cores: 4 L2 Cache (per core): 256 KB L3 Cache: 8 MB Memory: 4 GB Processor Interconnect Speed: 4.8 GT/s Boot ROM Version: IM111.0034.B02 SMC Version (system): 1.54f36 Serial Number (system): QP0050HK5PJ Hardware UUID: 9B65F400-F93C-5C35-A185-8404FE6EDB6F - Oh and I have a cable modem wireless connection to internet
Thank you so very much - your help means a lot to me and my little girl.