Teac TN-300 turntable, worth spending cash on a better cartridge or?

Well I have had this turntable for a while now, I bought it for the simple reason it had a built in phono amp and at the time my preamp did not have phono inputs so thought it was worth a try just to listen to some of my old vinyl.
Now I paid the princely sum of $151 shipped for it so was not expecting too much but......
I was honestly very happily surprised for such a budget price it sounded pretty darn good!
If there is any speed variation my old ears cannot detect it, the imaging, soundstage, vocals, guitars, piano etc all sound very natural and clean, yes maybe it is a little lacking in down low bass but for $151? No complaints whatsoever.
So fast forward to the new preamp with a phono stage and I am now using this table straight through into the preamp phono and to my ears it just sounds even better, much better than something of this price bracket has any right to tbh!
Now after re-discovering my vinyl it sets me wondering.
It came supplied with audio-technica AT95E VM cartridge and my question is would I just be throwing money away by buying a better cartridge? And if not what would be a good cartridge recommendation?
Or should i just keep playing and enjoying and save up for a decidedly more upmarket deck or is there another budget offering that anybody can suggest.
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Keep it and enjoy it!
Oh I am enjoying it, just wondered if spending any money on a better cartridge was money wasted or not? 
This is a nice upgrade!
I'd be for saving for an upgrade. However, you could try the Nagaoka MP110. And keep it for your new deck in time.
I have always been partial to Shure cartridges, that was the norm in England, stick a good Shure in a Garrard deck and you was in budget heaven
Not familiar with those but will be checking it out, have you used yourself?