I don't know the licensing and all that jazz (even if you self-host for your personal use it shouldn't matter). But, this paper[0] released a week ago claims " 99.3% of the performance level of ChatGPT while only requiring 24 hours of finetuning on a single GPU" (QLORA).
A quick test of the huggingface demo gives reasonable results[1]. The actual model behind the space is here[2], and should be self-hostable with reasonable effort.
0. https://arxiv.org/abs/2305.14314 1. https://huggingface.co/spaces/uwnlp/guanaco-playground-tgi 2. https://huggingface.co/timdettmers/guanaco-33b-merged
Guanaco is indeed very capable and can replace GPT 3.5 in almost all scenarios, based on my tests.
Easy way to self-host it is to use text-generation-webui[1] and 33B 4-bit quantized GGML model from TheBloke[2].