Don't use a regex to parse well-formed JSON like this. Use the builtin json.loads function to parse the JSON string into an in-memory list data structure. Then you can access the first element in the list with L[1] and the "price" key in that dictionary with L[1]["price"]:
>>> s = '[true,{"name":"NameofItem","amount":"1","price":100,"sellerName":"Sellername1", "sellerId":1},{"name":"NameofItem2","amount":"1","price":101,"sellerName":"Sellername2","sellerId":2},22250]'
>>> import json
>>> L = json.loads(s)
>>> L
[True, {'name': 'NameofItem', 'amount': '1', 'price': 100, 'sellerName': 'Sellername1', 'sellerId': 1}, {'name': 'NameofItem2', 'amount': '1', 'price': 101, 'sellerName': 'Sellername2', 'sellerId': 2}, 22250]
>>> L[1]["price"]
100
>>> type(L[1]["price"])
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