Is there a way to see player balance(tix and R$) in-game?

It's possible, you have to send a HTTP GET request to http://api.roblox.com/my/balance, which gives you your current ROBUX and Tix encoded in a JSON string.

Note that you can only do this from the server. If you want the information to be sent to the client you should use RemoteFunctions to exchange the information.

local httpService = game:GetService("HttpService")
local url = "http://api.roblox.com/my/balance"

local information = httpService:GetAsync(url)

--OPTIONAL if you want to decode the JSON string
local decodeJSON = assert(LoadLibrary("RbxUtility")).DecodeJSON


print( information )