Cyclocross stakes

Can’t recommend these guys enough.

https://www.tudorenvironmental.co.uk/facilities/fencing-products/temporary-fencing-barriers

No idea about cheapest - costs def mount up though if you need dozens (then storage etc)

I just did a quick google "race tape post pin polypost" which showed quite a few options (Mole??) but there may be better options around

Last time I bought a load for Cyclocross courses they came from a equine supplier, officially I think they are electric fence stakes. Can't find the receipt to get the specific company sorry.

Where abouts on the country are you? Local Cyclocross league might lend you a load if it's off season. Suppose it depends how many times you need to use them.

Edit these are cheap. https://www.moleonline.com/horizont-electric-fence-white-easy-poly-post-90cm-10-pack-1263761?srsltid=AfmBOoojLh6DFP2YtXh_gDUxs7rsaqdpVEcdbbrQUPym45txuSLgWqwL6-Y

Just buy short ones, and even then put the tapes fairly low down. Less prone to getting snapped or stretched by the wind if they are closer to the floor.

I helped set up and take down 800 that looked similar to this today:

https://www.ebay.co.uk/itm/174729215865?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=XccFHq-RStG&sssrc=4429486&ssuid=&var=473909798210&widget_ver=artemis&media=COPY

Agricultural merchant for electric fence stakes.