No. I don't see any reason to at this point. Nintendo has been very generous with leaf tickets. I've earned enough to buy:
The two extra crafting spots @80 each = 160
Four extra market boxes @10 each = 40
Twenty +5 Inventory slots @20 each = 400
Total 600 Tickets
...and I still have over 300 tickets right now. I could buy KK's chair but it seems kind of boring so I'll wait to see if something better comes along.
The key is to have patience and not waste tickets on crafting times or materials.
Note: Leveling up will get you to 12 market boxes and only 150 inventory slots. If you want the max inventory (250) it will cost 400 tickets.
I don't know what the max market box number is, I have found that 16 is plenty for me so I won't be buying any more.
No. It is tempting to buy those special items so K.K. and Tom Nook can come over, but that's a lot of money to spend on a game I feel like I'll get tired of in a month or so (already been playing it three weeks).
I bought the first 2 launch specials! Ultimately I'm using them to expand my slots & escalate long-time projects, so I don't actually think I'll need them as much once my camp is established.
Nope! I'm enjoying the game, but I don't plan to spend any money on it. It's fun, but not immersive enough to justify the use of my hard-earned dollars.