I was going to buy a Tanaka M24 for a while there but then a good deal came up elsewhere. Here's a list of parts I made for myself.
Tanaka M24 Full Parts List
-Tanak M24 SWS $420
-G&G Power Bolt $76
-King Arms 3.5-10X40 M3 Scope $72
-First Factory 6.03 Inner Barrel $62
-G&G Power Pack $50
-King Arms Spring Return Bipod $48
-KM Custom Magazine Part $39
-G&P 30mm Mount Rings $30
-G&G Knock Arm & Plunger Set $18
-KM Custom Impact Plate $14
-G&G Rubber Set $13
-G&G Valve Knocker $10
-G&G Striker Spring $4
-G&G Gas Connector Spring $4
TOTAL COST: $798 +Shipping
Tanaka M24 Practical Parts List
-Tanak M24 SWS $420
-King Arms 3.5-10X40 M3 Scope $72
-First Factory 6.03 Inner Barrel $62
-G&P 30mm Mount Rings $30
TOTAL COST: $584 +Shipping
Tanaka M24 Practical Parts List #2
-Tanak M24 SWS $420
-King Arms 3.5-10X40 M3 Scope $72
-King Arms Spring Return Bipod $48
-G&P 30mm Mount Rings $30
TOTAL COST: $570 +Shipping
Tanaka M24 Starter Parts List
-Tanak M24 SWS $420
-King Arms 3.5-10X40 M3 Scope $72
-G&P 30mm Mount Rings $30
TOTAL COST: $522 +Shipping
I myself would say the rubber set would help with accuracy and range. If you have a tightbore in then the rubber set will compliment it nicely.
G&G Power Bolt
http://www.wgcshop.com/pcart/shopper.php?itm=GG-PT-07087_cat_GG%20Parts
G&G Rubber Set
http://www.wgcshop.com/pcart/shopper.php?itm=GG-PT-07082_cat_GG%20Parts
G&G Power Pack
http://www.wgcshop.com/pcart/shopper.php?itm=GG-PT-07078_cat_GG%20Parts