Road/Tour Bike for a Month (or maybe more?)

[guy]

Hi Guys.

I'll be in Finland and Estonia in the next couple of weeks, and even though I'm somewhat new to cycling I'm participating in this 300km cycling tour (https://saimaacycletour.com).

I'd be in need of a bike for that, both for training in the upcoming month and (preferably) for the event itself. My budget is not huge, and I'm open both to long-term renting or buying.

I thought of the following options:
a. renting for a month from a bike shop
b. renting from an individual
c. buying second-hand (from a shop or an individual)
d. buying and then selling after a month (to the same shop?)

But unfortunately I'm not familiar at all with the bike market and options in your city. Could you tell me what's the best options are in your opinion? (e.g. local bike shop names, popular online marketplace website, etc.)

I am of 170cm height, so usually ride around 52cm frame size (but some 48 to 54 frames also work). I suppose an endurance Road Bike will work best, but CX and gravel also might work.

Thanks in advance! Looking forward to hear from you